Johnson Controls York YKEP Series User manual

Brand: Johnson Controls

Model: York YKEP Series

Type: User manual

CENTRIFUGAL LIQUID CHILLER

WITH ECONOMIZER COMPRESSOR

CONTROL CENTER OPERATION Form 160.77-02 (611) Form 160.77-02 (1111)

R-134a

Issue Date:

November 15, 2011

MODEL YKEP

2700 - 3200 TON

LD15301a

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

This equipment is a relatively complicated apparatus.

During installation, operation maintenance or service,

individuals may be exposed to certain components or

conditions including, but not limited to: refrigerants,

materials under pressure, rotating components, and

both high and low voltage. Each of these items has the

potential, if misused or handled improperly, to cause

bodily injury or death. It is the obligation and respon-

sibility of operating/service personnel to identify and

recognize these inherent hazards, protect themselves,

and proceed safely in completing their tasks. Failure

to comply with any of these requirements could result

in serious damage to the equipment and the property in

IMPORTANT!

READ BEFORE PROCEEDING!

GENERAL SAFETY GUIDELINES

which it is situated, as well as severe personal injury or

death to themselves and people at the site.

This document is intended for use by owner-authorized

operating/service personnel. It is expected that these

individuals possess independent training that will en-

able them to perform their assigned tasks properly and

safely. It is essential that, prior to performing any task

on this equipment, this individual shall have read and

understood this document and any referenced mate-

rials. This individual shall also be familiar with and

comply with all applicable governmental standards and

regulations pertaining to the task in question.

SAFETY SYMBOLS

The following symbols are used in this document to alert the reader to specific situations:

Indicates a possible hazardous situation

which will result in death or serious injury

if proper care is not taken.

Indicates a potentially hazardous situa-

tion which will result in possible injuries

or damage to equipment if proper care is

not taken.

Identies a hazard which could lead to

damage to the machine, damage to other

equipment and/or environmental pollu-

tion if proper care is not taken or instruc-

tions and are not followed.

Highlights additional information useful

to the technician in completing the work

being performed properly.

External wiring, unless specied as an optional connection in the manufacturer’s product line, is

not to be connected inside the control panel cabinet. Devices such as relays, switches, transducers

and controls and any external wiring must not be installed inside the control panel. All wiring must

be in accordance with Johnson Controls’ published specications and must be performed only by

a qualied electrician. Johnson Controls will NOT be responsible for damage/problems resulting

from improper connections to the controls or application of improper control signals. Failure to

follow this warning will void the manufacturer’s warranty and cause serious damage to property or

personal injury.

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

CHANGEABILITY OF THIS DOCUMENT

In complying with Johnson Controls’ policy for con-

tinuous product improvement, the information con-

tained in this document is subject to change without

notice. Johnson Controls makes no commitment to

update or provide current information automatically to

the manual owner. Updated manuals, if applicable, can

be obtained by contacting the nearest Johnson Controls

Service office.

Operating/service personnel maintain responsibility for

the applicability of these documents to the equipment.

If there is any question regarding the applicability of

these documents, the technician should verify whether

the equipment has been modified and if current litera-

ture is available from the owner of the equipment prior

to performing any work on the chiller.

ASSOCIATED LITERATURE

NOMENCLATURE

MANUAL DESCRIPTION FORM NUMBER

YKEP Installation & Re-assembly 160.77-N1

YKEP Unit Operation & Maintenance 160.77-O1

YKEP Control Center Operation 160.77-O2

YKEP Unit & Control Panel Renewal Parts 160.77-RP1

YKEP Installation Checklist 160.77-CL1

YKEP Startup Checklist 160.77-CL2

YKEP Wiring Diagram - Field Connections 160.77-PW1

YKEP Wiring Diagram - Unit Wiring and Field Control Modication 160.77-PW2

Liquid Cooled Solid State Starter - Operation 160.00-O2

Medium Voltage Variable Speed Drive (2300v - 6600v) - Operation 160.00-O6

Medium Voltage Variable Speed Drive (10,000v - 13,800v) - Operation 160.00-O8

Unit Mounted Medium Voltage Solid State Starter (2300v - 4160v) - Operation 160.00-O7

Long-Term Storage Requirements - General 50.20-NM1

Long-Term Storage Requirements - Field Preparation 50.20-NM5

Long-Term Storage - Periodic Checklist and Logs 50.20-CL5

* For both Primary and Economizer power supply: “-” = 60Hz and “5” = 50Hz

Primary Motor

Primary Power Supply *

Economizer Compressor

Primary Compressor

Economizer Motor

Economizer Power Supply *

Condenser

Modification LevelEvaporator

Special FeaturesModel

YKEP BD B5 K7 Q3 DL CF5 A S

LD15116

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

THIS PAGE INTENTIONALLY LEFT BLANK

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

TABLE OF CONTENTS

LIST OF TABLES

TABLE 1 - YKEP Control System Sensors .............................................................................................................18

TABLE 2 - Trend Pen Assignments .........................................................................................................................92

TABLE 3 - Modbus RTU Slot List ............................................................................................................................93

TABLE 4 - Status Line Messages and Colors ....................................................................................................... 109

TABLE 5 - LCSSS High Supply Line Voltage Thresholds ..................................................................................... 118

TABLE 6 - LCSSS Low Supply Line Voltage Thresholds ......................................................................................118

TABLE 7 - Over-Current Trip .................................................................................................................................123

SECTION 1 - YKEP CHILLER OVERVIEW ..............................................................................................................7

SECTION 2 - YKEP CONTROL CENTER INTRODUCTION ..................................................................................17

SECTION 3 - YKEP CONTROL PANEL OPERATION ........................................................................................... 21

Home Screen .................................................................................................................................................25

System Screen ...............................................................................................................................................28

Manual / Auto Stations Screen .......................................................................................................................32

Subcooler Screen ........................................................................................................................................... 34

Economizer Screen ........................................................................................................................................36

Evaporator Screen .........................................................................................................................................38

Hot Gas Screen .............................................................................................................................................. 40

Condenser Screen .........................................................................................................................................42

Primary Compressor Screen ..........................................................................................................................44

Primary Proximitor Calibration Screen ...........................................................................................................48

PRV Calibration Screen.................................................................................................................................. 50

Oil Sump Screen ............................................................................................................................................52

Primary Variable Geometry Diffuser Screen ...................................................................................................54

Primary Motor Screen (EM Starter) ................................................................................................................ 56

Primary Motor Screen (MV SSS) ...................................................................................................................58

Primary Motor Screen (MV VSD) ...................................................................................................................60

Capacity Controls Screen with Hot Gas (Fixed Speed) .................................................................................62

Capacity Controls Screen without Hot Gas (Fixed Speed) ............................................................................64

Capacity Controls Screen (Speed Option) .....................................................................................................66

Capacity Controls Screen (Vane Anti-Surge) .................................................................................................68

Primary Capacity Tuning Screen .................................................................................................................... 70

Primary Anti-Surge Screen ............................................................................................................................. 72

Capacity Limits Screen ...................................................................................................................................74

Economizer Compressor Screen ...................................................................................................................76

Economizer Motor LCSSS Screen .................................................................................................................78

Economizer Capacity Screen .........................................................................................................................80

Setpoints Screen ............................................................................................................................................82

Factory Setup Screen .....................................................................................................................................84

Comms Screen ...............................................................................................................................................86

Alarm History Screen .....................................................................................................................................88

Active Alarms Screen ..................................................................................................................................... 89

Trip Status Screen ..........................................................................................................................................90

Trending Screen ............................................................................................................................................. 91

SECTION 4 - MODBUS RTU SLOT LIST ...............................................................................................................93

SECTION 5 - DISPLAY MESSAGES .................................................................................................................... 109

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

FIGURE 1 - YKEP System Component Identication ...............................................................................................7

FIGURE 2 - YKEP Chiller System Diagram ..............................................................................................................8

FIGURE 3 - YKEP Chiller Operation Sequence Timing Diagram .............................................................................. 9

FIGURE 4 - YKEP Chiller Oil Management System ................................................................................................ 11

FIGURE 5 - Capacity Control Model .......................................................................................................................13

FIGURE 6 - System Anti-Surge Map ....................................................................................................................... 15

FIGURE 7 - Logic Controller....................................................................................................................................17

FIGURE 8 - Control Panel ....................................................................................................................................... 17

FIGURE 9 - YKEP Control System Sensors ...........................................................................................................19

FIGURE 10 - Red Lion Touch-Screen Display ........................................................................................................21

FIGURE 11 - Security Manager ...............................................................................................................................22

FIGURE 12 - Username ..........................................................................................................................................22

FIGURE 13 - Password ........................................................................................................................................... 22

FIGURE 14 - Setpoint Program Dialog Box ............................................................................................................23

FIGURE 15 - Menu Screen .....................................................................................................................................23

FIGURE 16 - Navigation ..........................................................................................................................................24

FIGURE 17 - Home Screen .....................................................................................................................................25

FIGURE 18 - System Screen ..................................................................................................................................28

FIGURE 19 - Manual / Auto Stations Screen ..........................................................................................................32

FIGURE 20 - Subcooler Screen ..............................................................................................................................34

FIGURE 21 - Economizer Screen ...........................................................................................................................36

FIGURE 22 - Evaporator Screen .............................................................................................................................38

FIGURE 23 - Hot Gas Screen .................................................................................................................................40

FIGURE 24 - Condenser Screen .............................................................................................................................42

FIGURE 25 - Primary Compressor Screen .............................................................................................................44

FIGURE 26 - Primary Proximity Calibration Screen ................................................................................................ 48

FIGURE 27 - PrV Calibration Screen ......................................................................................................................50

FIGURE 28 - Oil Sump Screen................................................................................................................................52

FIGURE 29 - Primary variable Geometry Diffuser Screen ......................................................................................54

FIGURE 30 - Primary Motor Screen (EM Starter) ...................................................................................................56

FIGURE 31 - Primary Motor Screen (MV SSS) .......................................................................................................58

FIGURE 32 - Primary Motor Screen (MV VSD) .......................................................................................................60

FIGURE 33 - Capacity Controls Screen (Fixed Speed with Hot Gas) .....................................................................62

FIGURE 34 - Capacity Controls Screen (Fixed Speed without Hot Gas) ................................................................64

FIGURE 35 - Capacity Controls Screen (Speed Option).........................................................................................66

FIGURE 36 - Capacity Controls Screen (Vane Anti-Surge) ..................................................................................... 68

FIGURE 37 - Primary Capacity Tuning Screen .......................................................................................................70

FIGURE 38 - Primary Anti-Surge Screen ................................................................................................................72

FIGURE 39 - Capacity Limits Screen ...................................................................................................................... 74

FIGURE 40 - Economizer Compressor Screen .......................................................................................................76

FIGURE 41 - Economizer Motor LCSSS Screen ....................................................................................................78

FIGURE 42 - Economizer Capacity Screen ............................................................................................................80

FIGURE 43 - Setpoints Screen ...............................................................................................................................82

FIGURE 44 - Factory Setup Screen ........................................................................................................................ 84

FIGURE 45 - Comms Screen .................................................................................................................................. 86

FIGURE 46 - Alarm History Screen ......................................................................................................................... 88

FIGURE 47 - Active Alarms Screen ......................................................................................................................... 89

FIGURE 48 - Trip Status Screen .............................................................................................................................90

FIGURE 49 - Trending Screen ................................................................................................................................91

FIGURE 50 - System Status / System Details.......................................................................................................109

LIST OF FIGURES

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

CHILLER PRINCIPLE OF OPERATION

The YKEP chiller (Figure 1 on Page 7) consists

of the components of a standard high pressure single

stage centrifugal chiller plus the addition of a flash

economizer and a secondary compressor to draw flash

gas from the economizer when required and discharge

to the condenser. The secondary compressor is referred

to as the economizer compressor. A system diagram is

shown in Figure 2 on Page 8.

The chiller operates in three configurations depending

on the lift required and the load.

1. The primary compressor can operate indepen-

dently with the economizer off, drawing suction

from the evaporator, discharging to the condenser,

with condensed liquid return to the evaporator via

ow through the idle economizer. The discharge

of the economizer compressor includes a check

valve to prevent backow from the condenser to

the economizer vessel in this operating mode.

2. When the calculated gas ow through the primary

compressor reaches a prescribed threshold as fol-

lows, the economizer compressor start is initiated.

The economizer compressor draws suction from

the economizer vessel and discharges to the con-

denser. The economizer compressor capacity is

controlled to maintain the economizer pressure at

a target value between the condenser and evapo-

rator pressures. In this mode the chiller is econo-

mizing to gain refrigeration effect for the primary

compressor and improve efciency.

Economizer compressor start criteria:

Primary Compressor Calculated Flow ≥ Flow Target de-

fined as a straight line between the points.

• Saturation Pressure of Subcooled Liquid - Evapo-

rator pressure = 64 PSID: 6000 CFM Required

• Saturation Pressure of Subcooled Liquid - Evapo-

rator Pressure = 30 PSID: 8200 CFM Required

Additionally:

• The Economizer Liquid Level must be below 90%

• The Leaving Chilled Liquid Temperature is not be-

low Setpoint

• The Economizer Saturation Temperature is not

below the Target Temperature

FIGURE 1 - YKEP SYSTEM COMPONENT IDENTIFICATION

LD15301

EVAPORATOR

CONDENSER

PRIMARY (K7)

COMPRESSOR

PRIMARY

OPEN-DRIVE

MOTOR

ECONOMIZER

OPEN-DRIVE

MOTOR

CONTROL

CENTER

ECONOMIZER (Q3)

COMPRESSOR

SUBCOOLER

VALVE

ISOLATION

VALVE

ECONOMIZER

COMPRESSOR

SOLID STATE

STARTER

ECONOMIZER

OIL PUMP

HOUSING

OIL PUMP

PANEL

SECTION 1 - YKEP CHILLER OVERVIEW

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 1 - YKEP CHILLER OVERVIEW

Economizer Compressor Stop criteria:

Primary Compressor Calculated Flow ≤ the prescribed

Start criteria line minus 2000 CFM

3. When the primary compressor capacity reaches

full capacity dened by either 100% input cur-

rent FLA or fully open PRV and full speed (VSD

starter types), the economizer compressor switch-

es to Boost operating mode. In this mode, the

economizer compressor capacity is controlled

to maintain leaving chilled liquid temperature

at setpoint and the primary compressor is given

a leaving chilled liquid temperature target 1 de-

gree F below the chiller setpoint to keep it fully

loaded. The economizer compressor is then con-

trolled to maintain the chiller programmed leav-

ing chilled liquid temperature setpoint using its

PRV’s. As additional capacity is required, the

economizer compressor draws the economizer

pressure lower, increasing the refrigeration effect

PRIMARY COMPRESSOR

CONDENSER

ECONOMIZER COMPRESSOR

ECONOMIZER

EVAPORATOR

CHILLED

LIQUID

(OPTIONAL)

HOT GAS

BYPASS VALVE

ECONOMIZER

LEVEL VALVE

ECONOMIZER

LEVEL

SUBCOOLER

LEVEL

COOLING

LIQUID

PRV

VGD

CHECK

VALVE

PRV

SUBCOOLER

LEVEL VALVE

FIGURE 2 - YKEP CHILLER SYSTEM DIAGRAM

LD16021

FORM 160.77-O2

ISSUE DATE: 11/15/2011

SECTION 1 - YKEP CHILLER OVERVIEW

JOHNSON CONTROLS

of the mass owing through the primary and in-

creasing chiller capacity. Upon unloading, when

the economizer compressor PRV closed switch is

activated, signifying the economizer compressor

is completely unloaded, or the economizer satu-

ration temperature is 0.5 Degrees F above what

the target saturation temperature would be for

economizing mode, the economizer compressor

switches back to economizing operation. Then

the primary compressor control returns to fol-

lowing the chiller programmed leaving chilled

liquid temperature and the economizer compres-

sor is following its target economizer pressure as

described in (2) above.

A timing diagram of the compressors’ start sequence

and shutdown is shown in Figure 3 on Page 9.

FIGURE 3 - YKEP CHILLER OPERATION SEQUENCE TIMING DIAGRAM

LD16023

0 10 13 45 50 110

(0.17) (0.22) (0.75) (0.83) (1.83)

VANES

CLOSED

MAN. OIL

PUMP

DISABLED

AUTO ZEROING DIFFERENTIAL

OIL PRESSURE TRANSDUCERS

** VANES CLOSING - TIME

DEPENDENT ON INITIAL

VANE POSITION

OIL PRESSURE CHECK

OIL PUMP ON

"SYSTEM

COASTDOWN"

"SYSTEM

SHUTDOWN"

TIME IN SECONDS (MINUTES)

DISPLAY

MESSAGE

"SYSTEM RUN"

"SYSTEM PRELUBE"

** "VANES CLOSING

BEFORE

SHUTDOWN"

ENERGIZE (OPEN)

LIQUID GEAR COOLING

SOLENOID (PRIMARY COMPRESSOR)

RESTART AFTER

ANTI-RECYCLE

(FOR EM STARTERS, 30 MIN)

(FOR VSD STARTERS, 5 STARTS THEN 10 MIN)

240 SEC

(4 MIN)

150 SEC

(2.5 MIN)

FLOW

SWITCH

BYPASS

START STOP

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 1 - YKEP CHILLER OVERVIEW

YKEP OIL MANAGEMENT

Figure 4 on Page 11 shows the layout of the chiller

oil management system. Each compressor has a dedi-

cated oil pump in a common oil sump with the other

pump. Oil for each is passed through its individual

oil cooler and filter set to the compressor bearings.

Each compressor has supervisory pressure monitoring

against the sump pressure to ensure sufficient supply to

its bearings. Refrigerant liquid flow to each oil cooler

is regulated with a thermostatic expansion valve sens-

ing oil temperature at the outlet of the cooler to 110° F.

Oil drains from the rotor support of each compressor

back to the sump. Oil to each compressor fills a drain-

down reservoir in the housing to provide coastdown oil

in the event of a power loss while running.

Oil temperature is maintained to a target 50° F above

condenser saturation temperature when the chiller is

not running. Electric oil heaters are operated by the

control system to accomplish this. At no time will the

control allow the oil heaters to continue to operate with

oil temperature above 160°F.

Oil return from the refrigerant system is accomplished

with a single eductor block. The block has three pas-

sages with eductor nozzles, all driven by condenser gas

from a common manifold within the block.

The venturi stream of each of the nozzles draws fluid

from:

• the evaporator

• the primary compressor PRV cavity in two adja-

cent locations

• the economizer compressor PRV cavity.

The outlet of the eductor sections goes to a common

plenum in the block and vented to the oil sump. The oil

sump is vented to the suction of the Primary compres-

sor behind the pre-rotation vanes.

The primary compressor is also supplied with liquid

refrigerant gear cooling that is initiated with a solenoid

valve that opens for compressor run.

FORM 160.77-O2

ISSUE DATE: 11/15/2011

SECTION 1 - YKEP CHILLER OVERVIEW

JOHNSON CONTROLS

FIGURE 4 - YKEP CHILLER OIL MANAGEMENT SYSTEM

LD16022

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 1 - YKEP CHILLER OVERVIEW

CAPACITY CONTROL OPERATION

Chiller Applications

Much of the function of the YKEP Control System is

dedicated to chiller capacity control. Sensors register

system conditions that are used to infer the total cool-

ing load and make necessary adjustments to the system

components. A complete list of sensors is shown in

Table 1 on Page 18.

There are two primary mechanisms by which cooling

capacity is controlled: pre-rotation vanes, and the hot

gas bypass valve. The primary directive of the Control

System is first to maintain safe operating conditions,

then to keep the system online, and finally to efficient-

ly maintain setpoints.

The interaction of capacity control subsystems is com-

plex, and can be better understood by referring to the Ca-

pacity Control Model shown in Figure 5 on Page 13.

The Capacity Control philosophy of the York YKEP

chiller control system allows efficient, fully automated

control, without need for operator intervention. The

YKEP control system is designed for industrial process

applications. This control system also monitors and

displays all safety aspects of the chiller and provides

alarms and a shutdown if safety limits are exceeded. If

operator intervention is required, manual controls are

provided on the Electronic Operator interface, for all

electric actuators.

The Capacity Controls algorithm automatically seeks

out the most efficient operation of the YKEP chiller. The

pre-rotation vanes are automated to obey the tempera-

ture controller to maintain process water production. In

cases of low load, the pre-rotation vanes automatically

throttle and are limited to a minimum anti-surge posi-

tion, which is calculated from a head curve. To provide

light duty operation, the hot gas recycle valve is seam-

lessly throttled open according to temperature demands.

This keeps the centrifugal compressor out of surge and

maintains process water production.

In cases of high load, which exceeds the motor current

usage, the capacity controls algorithm automatically

unloads the system to maintain a restriction on power

consumption. In the same way, conditions of high dis-

charge pressure or low suction pressure override the

production of process water in the interests of keeping

the chiller system online.

In cases of light load and low head, the economizer

compressor is dropped offline and the unit will be run

with the primary compressor like a single-stage YK

chiller.

In cases of high load, the economizer compressor is

brought back online to perform the additional gas com-

pression. The unit runs in compound mode with the

flash economizer in the cycle.

Start Up

When the chiller is started from shutdown, until the

Leaving Chilled Liquid Temperature comes within 2

degrees F of the Leaving Chilled Liquid Temperature

Setpoint the Hot Gas Bypass valve is driven closed at

a programmed ramp rate. When the Hot Gas Bypass

valve reaches full closed, the Primary compressor pre-

rotation vanes are driven open at a programmed ramp

rate. These program points are set on the Primary Ca-

pacity Tuning screen. When either; 1) the pre-rotation

vanes reach full open or 2) the LCHLT comes within 2

degrees F of setpoint, the ramp control stops and con-

trol of the Hot Gas valve and pre-rotation vanes switch-

es to the capacity control PID and anti-surge controls.

High current, low evaporator pressure or high condens-

er pressure overrides are always applicable when their

thresholds are exceeded.

Role of Hot Gas Bypass

The natural solution on a centrifugal chiller applica-

tion is that when the surge line is approached with a

decrease in load, the mass flow cannot be decreased

without aerodynamic instability; therefore the hot gas

bypass is used to supplement mass flow. This supple-

mental mass flow creates a source of inefficiency in

the refrigeration cycle and allows the chiller to run at

lower evaporator loads than it could without hot gas.

Major Capacity Control Devices

1. Compressor Pre-rotation Vanes

The compressor pre-rotation vanes (PRV's) are

internal guide vanes in the suction flow path to

the impeller wheel. The PRV's are used to throttle

the refrigerant flow through the system as a means

of controlling capacity in response to the leaving

chilled water temperature. If the leaving chilled

water temperature falls below the setpoint, the

PRV's are partially closed until the net cooling is

reduced and the leaving chilled water returns to

setpoint.

In the event of high motor power, the capacity

control signal is over-ridden and the compressor

PRV's are closed to keep the motor power down.

FORM 160.77-O2

ISSUE DATE: 11/15/2011

SECTION 1 - YKEP CHILLER OVERVIEW

JOHNSON CONTROLS

On start-up, the PRV's are closed to reduce the

starting load torque of the compressor.

The compressor pre-rotation vanes are closed on shut-

down to reduce backflow of high-pressure gas from

the condenser, which might otherwise cause the com-

pressor to spin backwards at a high rate of speed.

A shaded pole motor operates the mechanical

pre-rotation vane linkage, at the compressor. The

shaded pole motor is operated by a contact closure

to either open or close the vanes. A pre-rotation

vane position potentiometer senses the position of

the vanes and reports it to the controller as a per-

centage open value.

2. Hot Gas Bypass Valve

The hot gas bypass valve is used primarily at low

loads to maintain a minimum suction gas flow re-

quired by the compressor for stability. When the

compressor has reduced capacity to its minimum

flow (via pre-rotation vane throttling), further ca-

pacity reductions are accomplished by opening

the hot gas bypass valve. This maintains the flow

to the compressor by bypassing the discharge gas

back to the compressor suction.

However, the hot gas flow replaces the useful

evaporation in the cooler since the compressor

flow is at minimum. Thus, the net chilling capac-

ity is reduced (albeit not efficiently).

The minimum suction flow or minimum com-

pressor PRV position will vary. As the differential

“head” pressure is lowered (due to colder con-

denser water) the compressor is capable of stable

operation at lower loads. The programming in the

chiller panel thus uses the differential “HEAD”

pressure to establish when the hot gas may be

needed.

• On a water chilling application, this valve

goes open on shutdown.

FIGURE 5 - CAPACITY CONTROL MODEL

CHILLED WATER

TEMPERATURE

CONTROLLER

GREATER

THAN

SELECTOR

RATIO CONTROLLER

= 100-(100*LESS THAN

SELECTOR)/ANTISURGE)

HOT GAS

RECYCLE

VALVE

COMPRESSOR

PRE-ROTATION

VANES

ANTISURGE VANE

POSITION FOR A

GIVEN LIFT

CONDTION

LESS THAN

SELECTOR

MOTOR CURRENT LIMIT

CONTROLLER

(DOES NOT UNLOAD

LESS THAN ANTI-SURGE)

EVAPORATOR

PRESSURE

OVERRIDE

CONTROLLER

CONDENSER

PRESSURE

OVERRIDE

CONTROLLER

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 1 - YKEP CHILLER OVERVIEW

The hot gas valve is a disc type control valve with

an electric actuator. The control signal is a modu-

lating direct current signal, which is converted to a

position by an electric actuator. The valve will be

fully closed at low signal and open at high signal.

Refer to YKEP Wiring Diagram - Unit Wiring and

Field Control Modification (Form 160.77-PW2)

to see the 0-10 VDC Control Signal wiring. The

Output Scaling screen allows factory selection of

the proper output signal.

3. Subcooler Liquid Level Valve LCV-114

The subcooler liquid level valve controls the re-

frigerant liquid level in the subcooler located in

the bottom of the condenser to maintain the prop-

er amount of subcooling and provide the most ef-

ficient operation at all loads.

This valve is opened after shutdown to allow a

slow change in pressure between evaporator and

condenser. The pressure in the condenser forces

the liquid out of the condenser into the economiz-

er and the evaporator. It opens at start-up and then

slowly closes until it reaches the position dictated

by the liquid level control PID instruction in the

chiller controller.

The liquid level valve is a disc type control valve

with an electric actuator. The control signal is

modulated direct current, which is converted to a

position by an electric actuator. The valve will be

fully closed at low signal and open at high signal.

4. Economizer Liquid Level Valve LCV-116

The Economizer liquid level valve controls the

refrigerant liquid level in the economizer to main-

tain a good liquid seal between the flash gas in the

top of the economizer and the liquid to the evapo-

rator, this provides the most efficient operation at

all loads.

The liquid level valve is a disc type control valve

with an electric actuator. The control signal is

modulating direct current, which is converted to a

position by an electric actuator. The valve will be

fully closed at low signal and open at high signal.

Programmed Capacity Control Functions

Chilled Temperature Control

Using the input signal from a temperature sensor in the

leaving chilled water line, this control provides an out-

put signal, which decreases as water temperature drops

below set point to reduce the capacity of the chiller.

When override and anti-surge conditions are satis-

fied, the temperature control subsystem may dominate.

Since temperature control is the highest function as-

sociated with capacity control, its task must be con-

current and compliant with all other subsystems and

subsystem directives. It controls the hot gas valve, and

pre-rotation vanes in its attempt to maintain the chilled

water temperature setpoint while keeping the compres-

sor out of surge.

Dynamic Override Controls

Three operating parameters are primarily concerned

with the safe operation of the system: evaporator pres-

sure, condenser pressure, and motor load. If any of

these parameters were to exceed the limits defined by

the setpoints, it could lead to a shutdown of the chiller

by the safety setpoints. Maintaining chiller operation is

the function of the Dynamic Override subsystem.

The power override control function uses the motor

power input signals to limit capacity. When one of the

motor powers exceeds the setpoint, the control puts out

a decreasing signal. The Less Than Selector will then

pass this lower signal on to close the compressor pre-

rotation vanes, thus reducing the demand on the mo-

tor and returning the motor demand limit to below the

maximum threshold.

The pressure override systems prevent a system opera-

tion condition from shutting down a chiller premature-

ly. The pressure override loop controllers maintain the

chiller operation just within the safe operational limits

of the vessels, until system conditions return to design.

The condenser pressure override produces an unloading

effect on the chiller if the cooling water to the chiller

goes above design. If the chiller were not unloaded in

this condition, the discharge high-pressure cutout would

shut the chiller down, and no cooling would be done.

The low evaporator pressure override is a key override in

preventing the unit from either freezing or going down

on low evaporator conditions. A system overshoot, or a

low temperature transition in process water can result

in a low suction pressure condition. During startup, the

condensing pressure may initially be low. This can cause

low level in the evaporator, thereby reducing the heat ex-

changer performance, and lowering the evaporator pres-

sure. The low evaporator pressure override unloads the

chiller rapidly, and often opens the hot gas valve to try

to maintain a suction pressure in the chiller. As the fault

condition subsides, the override backs off and returns

the chiller to normal temperature controlled operation.

FORM 160.77-O2

ISSUE DATE: 11/15/2011

SECTION 1 - YKEP CHILLER OVERVIEW

JOHNSON CONTROLS

ANTI-SURGE, PRV

Keeping the compressor out of surge is the function

of the anti-surge subsystem. The anti-surge system is

based on a straight-line approximation of the compres-

sor surge curve (Figure 6 on Page 15).

The anti-surge line is biased to the right of the actual

surge line. When the compressor needs to move left on

the map, and move less mass flow, the vanes can only

be reduced so far, before a lack of mass flow causes

a surge condition. The anti-surge system supplements

mass flow to the compressor by using the Hot Gas By-

pass valve. This allows the chiller to be unloaded with-

out surge.

Once the anti-surge system has been set for the maxi-

mum head condition, and the minimum head condi-

tion, the compressor is restricted from surge. The point

represented by the intersection of VPD1 and MVP1 is

the worst case operating condition of the compressor,

with high head and low load. The other condition that

defines the anti-surge line is at low head and low load,

represented by the intersection of VPD2 and MVP2.

The shaded area of the left side of the map is the surge

area.

The vanes cannot close more than a given percentage

for a given head condition, defined by this line. As the

capacity control system unloads the chiller, the Hot

Gas Bypass valve is opened proportionally to maintain

stable operation and control the process.

SYSTEM ANTI-SURGE MAP

200

150

100

0 25 50 75 100

MVP2 MVP1

% VANES

VPD1

VPD2

FIGURE 6 - SYSTEM ANTI-SURGE MAP

LD15231

Anti-Surge (PRV) Calculation

The anti-surge tuning values are based on estimated

part load conditions and minimum vane signals re-

quired at these conditions to prevent unstable opera-

tion (surging):

Compressor

Differential

(Head) Pressure

Minimum PRV Signal

Setpoint for

Stable Operation

High Head

(PD1)

70 psid MVP1 = 8% Open

Low Head

(PD2)

30 psid MVP2 = 2% Open

It is very important that this control be

adjusted to suit chiller operating condi-

tions to achieve maximum efciency of

operation.

Anti-Surge (PRV) Tuning

• With the chiller running in automatic, take the

condensing conditions to the highest inlet tem-

perature attainable in the system (without tripping

on high discharge pressure). Increase tower inlet

temperature or reduce tower ow.

• At the highest condensing temperature, start re-

ducing the load on the chiller, by reducing the

ow, or decreasing the inlet temperature. This

will cause the capacity control system to back the

vanes in an unload sequence.

• If the chiller surges before the Hot Gas valve be-

gins to open, then the anti-surge line must move

right on the map.

• If the chiller never surges down to minimum load,

then the anti-surge parameters are adequate for

protection, but may not be most efcient.

• During the unload sequence, record the operating

head as VPD1.

• Increasing and decreasing the parameter MVP1

will move the anti-surge line right and left on the

map. Listen for a surge, and move the anti-surge

line right several percent, to increase refrigerant

ow, by supplementing hot gas.

• Repeat the procedure for low head operation.

• At the lowest condensing temperature, start reduc-

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 1 - YKEP CHILLER OVERVIEW

ing the load on the chiller, by reducing the ow, or

decreasing the inlet temperature. This will cause

the capacity control system to back the vanes in

an unload sequence.

• If the chiller surges before the Hot Gas valve be-

gins to open, then the anti-surge line must move

right on the map.

• If the chiller never surges down to minimum load,

then the anti-surge parameters are adequate for

protection, but may not be most efcient.

• During the unload sequence, record the operating

head as VPD2

• Increasing and decreasing the parameter MVP2

will move the anti-surge line right and left on the

map. Listen for a surge, and move the anti-surge

line right several percent, to increase refrigerant

ow, by supplementing hot gas.

The plant condenser water control system will deter-

mine the actual high and low head conditions depending

on the range of condenser water temperature allowed.

If actual operating conditions are different than those

shown above, you must enter the new values for the an-

ti-surge parameter calculation to produce the required

output signals.

The “ANTI-SURGE MIN PRV POS” output (Y%) is

calculated based on the actual calculated differential

pressure (head) as follows:

PD (Head) = (Compressor Discharge Pressure) – (Evaporator Pressure)

Y% = (PD-PD2) x (MVP1-MVP2) / (PD1-PD2) + MVP2

Hot Gas Control Tuning

The “HOT GAS CONTROL” operates to open the

valve as a decreasing load causes the “CHILLED WA-

TER TEMP. CONTROL” output to drop below the

“ANTI-SURGE MIN. PRV POSITION”.

ANTI-SURGE, SPEED

Chillers which employ a variable speed drive for the

primary compressor motor also use a speed anti-surge

subsystem. This system is based on a 4-segment line

approximation of the compressor full-open PRV surge

curve. The specifics can be visualized on the Primary

Anti-Surge Screen. Any required adjustments to the

speed anti-surge tuning should be performed before

adjusting the PRV anti-surge line.

Anti-Surge (Speed) Tuning

• With the chiller running in automatic, take the

condensing conditions to the highest inlet tem-

perature attainable in the system (without tripping

on high discharge pressure). Increase tower inlet

temperature or reduce tower ow.

• At the highest condensing temperature, start re-

ducing the load on the chiller, by reducing the

ow, or decreasing the inlet temperature. This

will cause the capacity control system to back the

primary compressor speed in an unload sequence.

• If the chiller surges before the PRV’s throttle

closed, then the anti-surge line must move right

on the map.

• If the chiller never surges down to minimum load,

then the anti-surge parameters are adequate for

protection, but may not be most efcient.

• During the unload sequence, record the operating

head as SPD1

• Increasing and decreasing the parameter MSP1

will move the anti-surge line right and left on the

map. Listen for a surge, and move the anti-surge

line right several percent, to increase speed.

• Repeat the procedure for low head operation.

• At the lowest condensing temperature, start reduc-

ing the load on the chiller, by reducing the ow, or

decreasing the inlet temperature. This will cause

the capacity control system to back the primary

compressor speed in an unload sequence.

• If the chiller surges before the PRV’s throttle

closed, then the anti-surge line must move right

on the map.

• If the chiller never surges down to minimum load,

then the anti-surge parameters are adequate for

protection, but may not be most efcient.

• During the unload sequence, record the operating

head as SPD5.

• Increasing and decreasing the parameter MSP5

will move the anti-surge line right and left on the

map. Listen for a surge, and move the anti-surge

line right several percent, to increase speed.

• Repeat the process as needed for head and mini-

mum speed points SPD2, SPD3, SPD4 and MSP2,

MSP3, MSP4 between the endpoints to further

dene the surge line.

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 2 - YKEP CONTROL CENTER INTRODUCTION

YKEP CONTROL CENTER

The YKEP Control Center is a fully integrated system

that monitors and controls all aspects of the chiller’s

components (see Figure 1 on Page 7) and opera-

tion. It provides all the necessary controls and control

logic to facilitate automatic start-up, automatic opera-

tion, capacity control, and safety protection. The Con-

trol Center has two components - the Logic Controller

and the Human-Machine Interface (HMI):

Logic Controller

The logic controller is a stand-alone Allen-Bradley

1769-L35E Compact Logix Programmable Automa-

tion Controller (PAC) (see Figure 7 on Page 17).

• The PAC controls all aspects of machine operation

by monitoring vital parameters and making real-

time adjustments as necessary to ensure safe and

efcient operation of system components.

LD15302

FIGURE 7 - LOGIC CONTROLLER

Control Panel

The control panel is a RedLion Controls Model

G310C230 10.4” color active matrix touchscreen dis-

play with seven front-panel push-buttons and three

front-panel LEDs (see Figure 8 on Page 17). The

control panel is a factory wired, unit mounted, NEMA

12, gasketed enclosure.

• The panel displays real-time chiller sensor data

via the PAC and allows for manual adjustments to

operational parameters.

FIGURE 8 - CONTROL PANEL

LD15303

OPERATOR INTERFACE

Operators access the chiller control system through

full-color screens that display real-time data from all

control system sensor points (see Figure 9 on Page

19) and are equipped with both sensor history log-

ging and complete alarm/system trip history features.

YKEP CONTROL CENTER FEATURES

The Control Center for YKEP is a Programmable Au-

tomation Controller (PAC) based control system for

YORK R134a centrifugal chillers. It controls the leav-

ing chilled liquid temperature and maintains required

pressure to avoid surge via pre-rotation vane controls,

motor drive speed and optional hot gas bypass. It has

the ability to limit motor current and shell pressures.

The Control Center comes configured with a full 10.4”

screen LCD touchscreen Graphic Display. The graphic

display allows the presentation of several operating pa-

rameters at once. In addition, the operator may view a

graphical representation of the historical operation of

the chiller as well as the present operation. For the nov-

ice user, the locations of various chiller parameters are

clearly and intuitively marked. Instructions for specific

operations are provided on many of the screens.

The graphic display also allows information to be rep-

resented in both English (temperatures in °F and pres-

sures in PSIG) and Metric (temperatures in °C and

pressures in BAR) mode. The advantages are most

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

SECTION 2 - YKEP CONTROL CENTER INTRODUCTION

apparent, however, in the ability to display many lan-

guages.

The Control Center continually monitors the system op-

eration and records the cause of any shutdowns (Safety,

Cycling or Normal). This information is recorded in

memory and is preserved even through a power failure

condition. The user may recall it for viewing at any time.

During operation, the user is continually advised of the

operating conditions by various status and warning mes-

sages. In addition, it may be configured to notify the

user of certain conditions via alarms. A complete listing

of shutdown, status, and warning messages is attached

in the Display Messages section of this book.

There are certain screens, displayed values, program-

mable Setpoints and manual controls shown in this book

that are for Service Technician use only. They are only

displayed when logged in at SERVICE access level or

higher. The Setpoints and parameters displayed on these

screens are explained in detail in YKEP Unit Service

(Form 160.77-M1). These parameters affect chiller op-

eration and should never be modified by anyone other

than a qualified Service Technician. They are shown in

this book for reference only.

Advanced Diagnostics and troubleshooting information

for Service Technicians are included in YKEP Control-

Center Service (Form 160.77-M2). Also included in the

Service manual are detailed descriptions of chiller fea-

tures, such as the Refrigerant Level Control, Hot Gas

Bypass, Remote Setpoints, and Variable Geometry Dif-

fuser.

The control center expands the capabilities of remote

control and communications. By providing a common

networking protocol through the Modbus RTU, YORK

Chillers not only work well individually, but also as a

team. This network protocol allows increased remote

control of the chiller, as well as 24-hour performance

monitoring via a remote site. In addition, compatibility

is maintained with the present network of BAS commu-

nications. The chiller also maintains the standard digital

remote capabilities as well. Both of these remote control

capabilities allow for the standard Energy Management

System (EMS) interface:

1. Remote Start

2. Remote Stop

3. Remote Leaving Chilled Liquid Temperature

Setpoint adjustment (4-20mA)

4. Remote Current Limit Setpoint adjustment

(4-20mA)

5. Remote “Ready to Start” Contacts

6. Safety Shutdown Contacts

7. Cycling Shutdown Contacts

TABLE 1 - YKEP CONTROL SYSTEM SENSORS

SENSOR DESCRIPTION

FSLL-100 Evaporator Chilled Liquid Flow Switch

FSLL-103 Condenser Water Flow Switch

LCV-114 Subcooler Level Valve Actuator

LCV-116 Economizer Level Valve Actuator

LE-114 Subcooler Refrigerant Level Sensor

LE-116 Economizer Level Sensor

PCV-112A Open/Close Primary Compressor VGD

PCV-112B Open/Close Primary Compressor VGD

PE-111 Evaporator Refrigerant Pressure

PE-113 Condneser Refrigerant Pressure

PE-116 Economizer Refrigerant Pressure

PE-140 Oil Sump Pressure

SENSOR DESCRIPTION

PE-141A Primary Compressor Oil Pump Pressure

PE-141B Economizer Compressor Oil Pump Pressure

PE-149A Primary Compressor Discharge Pressure

PE-149B Economizer Compressor Discharge Pressure

PSHH-113A

* Primary Compressor High Discharge

Pressure Cutout

PSHH-113B

* Economizer Compressor High Discharge

Pressure Cutout

PWM1 Primary Compressor Oil Pump Speed

PWM2 Economizer Compressor Oil Pump Speed

RST-100 Leaving Chilled Liquid Remote Setpoint

RST-160 Remote Demand Limit

FORM 160.77-O2

ISSUE DATE: 11/15/2011

SECTION 2 - YKEP CONTROL CENTER INTRODUCTION

JOHNSON CONTROLS

FIGURE 9 - YKEP CONTROL SYSTEM SENSORS

LD15304

CONDENSER

ECONOMIZER

EVAPORATOR

MOTOR

JUNCTION

BOX

PE-141A

TE-100

TE-101

PE-141B

ZS-142B

ZS-100B

TCV-100B

VSDA

VSDB

PWM1

PWM2

ZS-100A

TCV-100A

PE-111

PE-113

TE-111

ZE-100A

PE-149B

PE-149A

TE-113

TE-112

FSLL-100

ZE-100B

PCV-112B

ZE-149B

PCV-112A

ZE-149A

PE-116

LE-116

LCV-116

LCV-114

TE-114

LE-114

TE-102

PE-140

TE-140

TE-103

FSLL-103

* Not Shown

SENSOR DESCRIPTION

TCV-100A Open/Close Primary Compressor PRV

TCV-100B Open/Close Economizer Compressor PRV

TCV-100C * Hot Gas Valve Actuator (Optional)

TE-100 Leaving Chilled Liquid Temperature

TE-101 Entering Chilled Liquid Temperature

TE-102 Entering Condenser Water Temperature

TE-103 Leaving Condenser Water Temperature

TE-111 Evaporator Refrigerant Liquid Temperature

TE-112 Primary Compressor Discharge Temperature

TE-113

Economizer Compressor Discharge

Temperature

TE-114 Subcooled Refrigerant Liquid Temperature

TE-140 Oil Sump Temperature

VSDA

Primary Compressor Main Oil Pump Drive

Faulted

SENSOR DESCRIPTION

VSDB

Economizer Compressor Main Oil Pump

Drive Faulted

XE-149A

* Primary Compressor VGD Stall Board

Signal

XE-149B

* Economizer Compressor VGD Stall

Board Signal

ZE-100A Primary Compressor PRV POT

ZE-100B Economizer Compressor PRV POT

ZE-142A Primary Compressor Axial Thrust Position

ZE-149A Primary Compressor VGD Position Pot

ZE-149B Economizer Compressor VGD Position Pot

ZS-100A Primary Compressor PRV Closed Limit Switch

ZS-100B

Economizer Compressor PRV Closed Limit

Switch

ZS-142B Economizer Compressor Thrust Switch

FORM 160.77-O2

ISSUE DATE: 11/15/2011

JOHNSON CONTROLS

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Johnson Controls York YKEP Series User manual

Johnson Controls York YKEP Series User manual

Johnson Controls York YKEP Series User manual

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