McQuay AGS 450D Operating instructions

Brand: McQuay

Model: AGS 450D

Type: Operating instructions

This manual is also suitable for

AGS 225D

Operating Manual

OM AGSD-2

Group: Chiller

Part Number: 331375401

Date: July 2007

Supercedes: OM AGSD-1

Air-Cooled Screw Compressor Chiller

AGS 225D through AGS 450D

Software Version AGSG30101D

60 Hertz, R-134a

2 OM AGSD-1

Table of Contents

Controller Features ...................................4

General Description...................................5

Control Panel Layout...............................5

Definitions...............................................6

Component Description.............................9

Hardware Structure..................................9

System Architecture...............................10

Sequence of Operation ............................11

Controller Operation...............................17

CP1 Inputs/Outputs ...............................17

Expansion I/O Controller 1 ...................18

Expansion I/O Controller 4 ...................19

Expansion I/O Controller 3 ...................19

Controller CP2.......................................20

Expansion I/O Controller 5 ...................21

Expansion I/O Controller 8 ...................22

Setpoints................................................22

Controller Functions ...............................26

Parameter Definitions............................26

Unit Enable............................................26

Unit Mode Selection..............................28

Unit States .............................................29

Ice Mode Start Delay.............................30

Evaporator Pump Control......................30

Leaving Water Temperature (LWT) Reset

...............................................................

Unit Capacity Overrides........................ 33

Building Automation System Interface. 34

Circuit Functions..................................... 39

Calculations........................................... 39

Compressor Control.............................. 40

Condenser Fan Control ......................... 45

EXV Control......................................... 47

Economizer Control.............................. 50

Alarms and Events.................................. 51

Unit Stop Alarms................................... 51

Unit Events............................................ 52

Circuit Stop Alarms............................... 52

Circuit Events........................................ 56

Alarm Logging...................................... 57

Event Logging....................................... 57

Using the Controller................................ 58

Security................................................. 60

Editing Setpoints................................... 61

Clearing Alarms .................................... 61

Unit Controller (CP1) Screens.............. 61

Editing Review...................................... 73

Start-up and Shutdown........................... 74

Temporary Shutdown............................ 74

Extended (Seasonal) Shutdown ............ 75

Field Wiring Diagram............................. 78

Information in this manual covers the McQuay International products at the time of publication and we reserve the right to make

changes in design and construction at anytime without notice.

 The following are trademarks or registered trademarks of their respective companies: BACnet from ASHRAE; L

ONMARK and LONWORKS from Echelon

Corporation; Modbus from Gould, Inc.; McQuay and MicroTech II from McQuay International.

Unit controllers are LONMARK

certified with an optional

LONWORKS

communications module

Manufactured in an ISO Certified facility

OM AGSD-1 3

This manual provides setup, operating, and troubleshooting information for the McQuay

MicroTech  controller for Model AGS-D vintage, air-cooled, rotary screw compressor

chillers. Please refer to the current version of the installation and maintenance manual IMM

AGSD (available on

www.mcquay.com) for information relating to the unit itself.

Software Version: This manual covers units with Software Version AGSG30101B. The

unit’s software version number can be viewed by pressing the MENU and ENTER keys (the

two right keys) simultaneously. Then, pressing the MENU key will return to the Menu

screen.

BOOT Version: 3.01F

BIOS Version: 3.62

WARNING

Electric shock hazard. Can cause personal injury or equipment damage.

This equipment must be properly grounded. Connections to, and service of,

the MicroTech II control panel must be performed only by personnel who are

knowledgeable in the operation of the equipment being controlled.

CAUTION

Static sensitive components. A static discharge while handling electronic

circuit boards can cause damage to the components. Discharge any static

electrical charge by touching the bare metal inside the control panel before

performing any service work. Never unplug any cables, circuit board terminal

blocks, or power plugs while power is applied to the panel.

NOTICE

This equipment generates, uses and can radiate radio frequency energy and,

if not installed and used in accordance with this instruction manual, can

cause interference to radio communications. Operation of this equipment in

a residential area can cause harmful interference, in which case the user will

be required to correct the interference at the user’s own expense.

McQuay International Corporation disclaims any liability resulting from any

interference or for the correction thereof.

Temperature and Humidity Limitations

The MicroTech  controller is designed to operate within an ambient temperature range of

-20F to +149°F (-29C to +65.1°C) with a maximum relative humidity of 95% (non-

condensing).

Language

This version of the software is set up for English language and inch-pounds units of measure

only.

4 OM AGSD-1

Controller Features

 Readout of the following temperature and pressure readings:

 Entering and leaving chilled water temperature

 Saturated evaporator refrigerant temperature and pressure

 Saturated condenser temperature and pressure

 Outside air temperature

 Suction line, liquid line, and discharge line temperatures  calculated superheat for

discharge and suction lines

 Oil pressure

 Automatic control of primary and standby chilled water pumps. The control will start one

of the pumps (based on lowest run-hours) when the unit is enabled to run (not necessarily

running on a call for cooling) and when the water temperature reaches a point of freeze

possibility.

 Two levels of security protection against unauthorized changing of setpoints and other

control parameters.

 Warning and fault diagnostics to inform operators of warning and fault conditions in plain

language. All events and alarms are time and date-stamped for identification of when the

fault condition occurred. In addition, the operating conditions that existed just prior to an

alarm shutdown can be recalled to aid in isolating the cause of the problem.

 Twenty-five previous alarms and related operating conditions are available.

 Remote input signals for chilled water reset, demand limiting, and unit enable.

 Test mode allows the service technician to manually control the controllers’ outputs and

can be useful for system checkout.

 Building Automation System (BAS) communication capability via L

ONWORKS,

Modbus, or BACnet standard protocols for all BAS manufacturers-simplified with

McQuay’s Protocol Selectability feature.

 Pressure transducers for direct reading of system pressures. Preemptive control of low

evaporator pressure conditions and high discharge temperature and pressure to take

corrective action prior to a fault trip.

OM AGSD-1 5

General Description

Control Panel Layout

The control panel is located on the front of the unit, to the left of the power panel.

Figure 1, Control Panel Components

Expansion Valve

Drivers

Circuit Breakers

MicroTech II

Controller, CP1

MicroTech II Controller,

CP2,

On Three-Compressor

Units Only

Switches & Fuses

Terminal Blocks

6 OM AGSD-1

Definitions

Active Setpoint

The active setpoint is the setting in effect at any given moment. This variation occurs on

setpoints that can be altered during normal operation. Resetting the chilled water leaving

temperature setpoint by one of several methods, such as return water temperature, is an

example.

Active Capacity Limit

The active setpoint is the setting in effect at any given moment. Any one of several external

inputs can limit a compressor’s capacity below its maximum value.

Condenser Saturated Temperature Target

The saturated condenser temperature target is calculated by first using the following

equation:

Sat condenser temp target raw = 0.833(evaporator sat temp) + 68.34

The “raw” value is the initial calculated value. This value is then limited to a range defined

by the Condenser Saturated Temperature Target minimum and maximum setpoints. These

setpoints simply cut off the value to a working range, and this range can be limited to a

single value if the two setpoints are set to the same value.

Dead Band

The dead band is a range of values surrounding a setpoint such that a change in the variable

occurring within the dead band range causes no action from the controller. For example, if a

temperature setpoint is 44F and it has a dead band of  2 degrees F, nothing will happen

until the measured temperature is less than 42F or more than 46F.

DIN

Digital input, usually followed by a number designating the number of the input.

Discharge Superheat

Discharge superheat is calculated for each circuit using the following equation:

Discharge Superheat = Discharge Temperature – Condenser Saturated Temperature

Error

In the context of this manual, “Error” is the difference between the actual value of a variable

and the target setting or setpoint.

Evaporator Approach

The evaporator approach is calculated for each circuit. The equation is as follows:

Evaporator Approach = LWT – Evaporator Saturated Temperature

See page 38 for more details

Evap Recirc Timer

A timing function, with a 30-second default, that holds off any reading of chilled water for

the duration of the timing setting. This delay allows the chilled water sensors (especially

water temperatures) to take a more accurate reading of the chilled water system conditions.

EXV

Electronic expansion valve, used to control the flow of refrigerant to the evaporator,

controlled by the circuit microprocessor.

OM AGSD-1 7

High Saturated Condenser – Hold Value

High Cond Hold Value = Max Saturated Condenser Value – 5 degrees F

This function prevents the compressor from loading whenever the pressure approaches

within 5 degrees of the maximum discharge pressure. The purpose is to keep the

compressor online during periods of possibly temporary elevated pressures.

High Saturated Condenser – Unload Value

High Cond Unload Value = Max Saturated Condenser Value – 3 degrees F

This function unloads the compressor whenever the pressure approaches within 3 degrees of

the maximum discharge pressure. The purpose is to keep the compressor online during

periods of possibly temporary elevated pressures.

Light Load Stg Dn Point

The percent load point at which one of two operating compressors will shut off, transferring

the unit load to the remaining compressor.

Load Limit

An external signal from the keypad, the BAS or a 4-20 ma signal that limits the compressor

loading to a designated percent of full load. Frequently used to limit unit power input.

Load Balance

Load balance is a technique that equally distributes the total unit load among the running

compressors on a unit or group of units.

Low Ambient Lockout

Prevents the unit from operating (or starting) at ambient temperatures below the setpoint.

Low Pressure Unload Setpoint

The psi evaporator pressure setting at which the controller will unload the compressor until

a preset pressure is reached.

Low Pressure Hold Setpoint

The psi evaporator pressure setting at which the controller will not allow further compressor

Low/High Superheat Error

The difference between actual evaporator superheat and the superheat target.

LWT

Leaving water temperature. The “water” is any fluid used in the chiller circuit.

LWT Error

Error in the controller context is the difference between the value of a variable and the

setpoint. For example, if the LWT setpoint is 44F and the actual temperature of the water

at a given moment is 46F, the LWT error is +2 degrees.

LWT Slope

The LWT slope is an indication of the trend of the water temperature. It is calculated by

taking readings of the temperature every few seconds and subtracting them from the

previous value, over a rolling one minute interval.

Milli-second

Maximum Saturated Condenser Temperature

The maximum saturated condenser temperature allowed is calculated based on the

compressor operational envelope.

8 OM AGSD-1

OAT

Outside ambient air temperature

Offset

Offset is the difference between the actual value of a variable (such as temperature or

pressure) and the reading shown on the microprocessor as a result of the sensor signal.

pLAN

Peco Local Area Network is the proprietary name of the network connecting the control

elements.

Refrigerant Saturated Temperature

Refrigerant saturated temperature is calculated from the pressure sensor readings for each

circuit. The pressure is fitted to an R-134a temperature/pressure curve to determine the

saturated temperature.

Soft Load

Soft Loading is a configurable function used to ramp up the unit capacity over a given time

period, usually used to influence building electrical demand by gradually loading the unit.

Setpoint

SSS

Solid state starter as used on McQuay screw compressors.

Suction Superheat

Suction superheat is calculated for each circuit using the following equation:

Suction Superheat = Suction Temperature – Evaporator Saturated Temperature

See page 38 for details.

Stage Up/Down Accumulator

The accumulator can be thought of as a bank storing occurrences that indicate the need for

an additional fan.

Stageup/Stagedown Delta-T

Staging is the act of starting or stopping a compressor or fan when another is still operating.

Startup and Stop is the act of starting the first compressor or fan and stopping the last

compressor or fan. The Delta-T is the “dead band” on either side of the setpoint in which no

action is taken.

Stage Up Delay

The time delay from the start of the first compressor to the start of the second.

Startup Delta-T

Number of degrees above the LWT setpoint required to start the first compressor.

Stop Delta-T

Number of degrees below the LWT setpoint required for the last compressor to stop.

VDC

Volts, Direct current, sometimes noted as vdc.

OM AGSD-1 9

Component Description

Hardware Structure

The controllers are fitted with a 16-bit microprocessor for running the control program.

There are controller terminals for connection to the controlled devices (for example:

solenoid valves, expansion valves, chilled water pumps). The program and settings are

saved permanently in FLASH memory, preventing data loss in the event of power failure

without requiring a back-up battery. The controllers also have optional remote

communication access capability for a BAS interface using standard protocols.

The Advanced MicroTech II controllers used on AGS-D chillers are not interchangeable

with previous MicroTech II controllers.

Keypad

A 4-line by 20-character liquid crystal display and 6-button keypad are mounted on the unit

and compressor controllers.

Figure 2, Keypad

Air Conditioning

LARM

VIEW

SET

Advanced

The four arrow keys (UP, DOWN, LEFT, RIGHT) have three modes of use.

1. Scroll between data screens in the direction indicated by the arrows (default mode).

2. Select a specific data screen in the menu matrix using dynamic labels on the right side

of the display such as ALARM, VIEW, etc. (pressing the MENU key enters this mode).

For ease of use, a visual pathway connects the appropriate button to its respective label

on the screen.

3. Change field values in setpoint programming mode as follows:

LEFT key = Default (D) RIGHT key = Cancel (C)

UP key = Increase (+) DOWN key = Decrease (-)

These four programming functions are indicated by a one-character abbreviation ( ) on the

right side of the display. This programming mode is entered by pressing the ENTER key.

vary an electric motor’s speed.

See the “

Using the Controller” section beginning on page 58 for detailed instruction on

controller operation.

MENU Key Left Arrow w/ Red Alarm Light Behind

ARROW Keys (4)

ENTER Key

10 OM AGSD-1

System Architecture

 One large controller (CP1) is used on 2 circuit chillers (AGS 225 through 300) and a

second large controllers (CP2) is added on 3 circuit chillers (AGS 330 through 450).

 Expansion I/O boards are used and communicate via a tLan (J23). Two are used on 2

circuit chillers and four are used on 3 circuit chillers. Expansion I/O board #3 is used

when additional pump or circuit status enable options are ordered.

A block diagram is shown below

Figure 3, System Block Diagram

NOTE: RAI=Remote Access Interface, EXB=Expansion Board

Table 1, pLAN Addressing

A pLAN is used to connect CP1 and CP2.

Controller Address Dip Sw 1 Position Dip Sw 2 Position Dip Sw 3 Position

Large 1 (CP1) 1 Up Down Down

Large 2 (CP2) 2 Down Up Down

Table 2, tLAN Addressing

A tLAN is used to connect the expansion modules to CP1 and CP2

Controller Expansion Serial Address

Large 1 PCOe1 1

Large 1 PCOe3 3

Large 1 PCOe4 4

Large 2 PCOe5 1

Large 2 PCOe8 4

BAS

Interface-

Bacnet,

Modbus

Large

Controller CP1

4X2

Large

Controller CP2

(

4X20LCD

RS485

/Lon

Expansion

I/O (EXB5)

Expansion

I/O (EXB8)

RS485

Expansion

I/O (EXB4)

Expansion

I/O (EXB3)

RS485

pLAN

Expansion

I/O (EXB1)

RAI

Service

Tool(option)

OM AGSD-1 11

Sequence of Operation

Figure 4, Unit Sequence of Operation (see Figure 4 for circuit sequence of operation)

Is unit enabled?

Is flow present?

Evaporator pump output on

Wait for chilled water loop to

recirculate.

Is there enough load to

start chiller?

Start first circuit.

Yes

Unit power up

Unit in Off state

The chiller may be disabled via the unit switch, the remote switch, the keypad

enable setting, or the BAS network. In addition, the chiller will be disabled if both

circuits are disabled, either because of an alarm or the circuit pumpdown switch on

each circuit, or if there is a unit alarm. If the chiller is disabled, the unit status

display will reflect this and also show why it is disabled.

If the unit switch is off, the unit status will be

Off:Unit Switch

. If the chiller is

disabled due to network command, the unit status will be

Off:BAS Disable

. When

the remote switch is open, the unit status will be

Off:Remote Switch

. When a unit

alarm is active, the unit status will be

Off:Unit Alarm

. In cases where no circuits

are enabled, the unit status will be

Off:All Cir Disabled

If the chiller is enabled, then the unit will be in the Auto state and the evaporator

water pump output will be activated.

After establishing flow, the chiller will wait some time to allow the chilled water loop

to recirculate for an accurate reading of the leaving water temperature. The unit

status during this time is

Auto:Evap Recirc

The chiller will then wait for the flow switch to close, during which time the unit

status will be

Auto:Wait for flow

Keep pump output on while

unit is enabled.

The chiller is now ready to start if enough load is present. If the LWT is not high

enough to start, the unit status will be

Auto:Wait for load

If the LWT is high enough to start, the unit status will be

Auto

. A compressor can

start at this time.

The first circuit to start is generally the available circuit with the least number of

starts, or the lowest numbered circuit if there is a tie. This circuit will go through its

start sequence at this point.

12 OM AGSD-1

Is more capacity

needed to satisfy load?

Has the stage up time

delay expired?

Start next circuit.

Yes

Load/unload as needed to

satisfy load.

Yes

Load/unload as needed to

satisfy load.

Can less circuits handle

the load?

Yes

Shut down one circuit.

Load/unload as needed to

satisfy load.

Is load satisfied?

Shut down last circuit.

Yes

The first circuit will load and unload as needed in an attempt to satisfy the load. It

will eventually get to a point where it is considered to be at full load. A circuit is at

full load when it reaches 75% slide target, it reaches the max slide target setting, or

it encounters a problem and is running in an inhibited state.

A minimum time must pass between the starting of circuits.

As the load drops off, the circuits will unload accordingly. If the LWT gets low

enough, or all running circuits unload enough, one circuit can shut off. This can

occur with either two or three circuits running.

When only one circuit is running, the load may drop off to the point where even

minimum unit capacity is too much. The load has been satisfied when the LWT

drops below the shutdown point. At this time the only running circuit can shut down.

All running circuits will now load/unload as needed to satisfy the load. In addition,

they will load balance so that both circuits are providing nearly equal capacity.

The second circuit will go through its start sequence at this point.

Note that a third circuit can be started if available. The two preceding conditions

must again be satisfied after starting the second circuit before starting the third

circuit.

The next circuit to shut off is generally the one with the most run hours.

The remaining running circuit(s) will load/unload as needed to satisfy the load.

The last circuit running now shuts down.

The unit should be ready to start again when the LWT gets high enough. The unit

status at this time will be

Auto:Wait for load

If a single circuit is not enough to satisfy the load, additional circuits will need to be

started.

OM AGSD-1 13

Figure 5, Circuit Sequence of Operation

Next on?

Next off?

Start Compressor

Stage down now?

Pumpdown circuit

Yes

Unit power up

Circuit is in Off state

When in the Run state, the compressor will load/unload as needed to satisfy the

load. The compressor will also load/unload to load balance with other compressors

that are running and not in a limited condition. However, it cannot load up until the

discharge superheat has been over 22 F for at least 30 seconds. After this, the

circuit status will be

Run:Normal

The EXV will operate in either Pressure Control or Superheat Control. In Pressure

Control, the evaporator pressure is controlled to a target pressure, which is adjusted

based on LWT and discharge superheat. In Superheat Control, the suction

superheat is controlled to a target that varies with discharge superheat.

Fans will be staged on and off, and if available the VFD speed will be modulated, to

control the condenser pressure. The condenser pressure is controlled to a target

that is based on evaporator pressure, with the target getting higher as the

evaporator pressure gets higher.

Stage up now?

Yes

Run Compressor

When the compressor starts, the EXV will open and begin controlling the evaporator

pressure. Depending on the OAT, a number of fans may be started with the

compressor to keep condenser pressure from climbing too fast. The circuit status

will normally be

Run: Disc SH Low

immediately after the compressor starts.

This compressor will be next on if it has the least starts of the compressors that are

not running and are available to run.

If there is a need for more cooling capacity, the compressor designated as next on

can start.

If this compressor has the most run hours of the running compressors, then this

compressor will be designated as the next one off.

If less cooling capacity is needed, the compressor designated as next off can shut

down. This condition may arise when either the LWT has dropped far enough below

the active set point or all circuits are running at a low capacity.

When the circuit does a normal shutdown, a pumpdown is performed. The EXV is

closed while the compressor continues to run. As soon as the pumpdown is

initiated, the compressor is unloaded to the minimum. The condenser fans

continue to control normally during this process. The circuit status during this time

Run:Pumpdown

After the evaporator pressure drops below the pumpdown pressure or enough time

has passed, the compressor and fans are shut off to end the pumpdown process.

The circuit status will normally be

Off:Cycle Timers

at this time.

When the circuit is in the Off state the EXV is closed, compressor is off, and all fans

are off.

If the compressor is ready to start when needed, the circuit status will be

Off:Ready

. When the circuit switch is off, the circuit cannot start and the status will

Off:Pumpdown Switch

14 OM AGSD-1

Off Conditions

Power is supplied to the power section of the electric panel. The standard power connection

is two (or three on models 330 to 450) separate sources, one to each circuit. Optionally, the

power may be supplied to a single power connection, either a power block or optional

disconnect switch.

With power supplied to the unit, 115 VAC power is applied through the control fuse F1 to

the compressor heaters, HTR1 and HTR2, evaporator heater, and the primary of the 24V

control circuit transformer.

CAUTION

Compressor heaters must be on for at least 12 hours prior to start-up

to avoid compressor damage.

The 24V transformer provides power to the MicroTech II controller and related components.

With 24V power applied, the controller will check the position of the front panel system

switch Q0. If the switch is in the "stop" position, the chiller will remain off, and the display

will indicate the operating mode to be OFF: Unit Switch. The controller will then check

the pumpdown switches. If any of the switches are in the "stop" position, that circuit’s

operating mode will be displayed as OFF: Pump Down Switch. If the switches for both

circuits are in the "Stop" position, the unit status will display OFF: All Circuits Disabled.

If the remote start/stop switch is open the chiller will be OFF: Remote Switch. The chiller

may also be commanded off via communications from a separate communicating panel such

as a BAS protocol interface. The display will show OFF: BAS Disable if this operating

mode is in effect.

If an alarm condition exists which prevents normal operation of both refrigerant circuits, the

chiller will be disabled and the display will indicate OFF: Unit Alarm. If the control mode

on the keypad is set to "Manual Unit Off," the chiller will be disabled and the unit status

will display OFF: Keypad Disable.

Alarm

The red alarm light in back of the left arrow key on the controller will be illuminated when

one or more of the cooling circuits has an active alarm condition which results in the circuit

being locked out or a unit alarm is active and manual reset is required. If only a circuit

alarm is active, the remaining circuits will operate as required. Events (low-level

occurrences) will not cause the key to light.

Start-up

If none of the above "off" conditions are true, the MicroTech II controller will initiate a start

sequence and energize the chilled water pump output relay. The chiller will remain in the

WaitForFlow mode until the field-installed flow switch indicates the presence of chilled

water flow. Once flow is established, the controller will sample the chilled water

temperature and compare it against the Leaving Chilled Water Setpoint, the Control Band,

and the Start-up Delta-Temperature, which have been programmed into the controller’s

memory.

If the leaving chilled water temperature is above the Active Chilled Water Setpoint plus the

adjustable Start-up Delta-T, the controller will select the refrigerant circuit with the lowest

number of starts as the lead circuit and initiate a start request. The circuit controller will

open the EXV and start the compressor. A green light under the Enter key on the circuit

controller will illuminate to indicate that the compressor is running.

If additional cooling capacity is required, the controller will activate additional cooling. As

the system load increases, the controller will start the lag refrigerant circuit when the lead

circuit reaches 75%, or some other capacity limit is reached, and the interstage timers are

satisfied. The compressors and capacity control solenoids will automatically be controlled

as required to meet the cooling needs of the system.

OM AGSD-1 15

The electronic expansion valves are operated by the MicroTech II controller to maintain

precise refrigerant control to the evaporator at all conditions.

Standard FanTrol Condenser Fan Control

When the compressor starts, a number of fans may be started, depending on the OAT and

the Forced Fan setpoints. The MicroTech II controller will activate the remaining condenser

fans as needed to maintain proper condenser pressure. The MicroTech II controller

continuously monitors the condenser pressure and will adjust the number of operating

condenser fans as required. The number of condenser fans operating will vary with outdoor

temperature and system load. The condenser fans are matched to the operating compressors

so that when a compressor is off, all fans for that circuit will also be off.

Pumpdown

As the system chilled water load requirements diminish, the compressors will unload. As

the system load continues to drop, the electronic expansion valve will be stepped closed, the

solenoid valve will close, and the refrigerant circuits will go through a pumpdown sequence.

As the evaporator pressure falls below the pumpdown pressure setpoint while pumping

down, the compressor and condenser fans will stop. The unit has a one-time pumpdown

control logic; therefore, if the evaporator pressure rises while the compressor is in the off

state, the controller will not initiate another pumpdown sequence. The circuit controller will

keep the compressor off until the next call for cooling occurs.

The chilled water pump output relay will generally remain energized until the unit is in the

Off State due to the remote stop switch, unit Off switch, BAS command, or keypad setting

calling for the unit to be disabled.

Liquid Line Solenoid Valve (LLSV)

The LLSV cycles with the compressor starter. Its purpose is to provide a positive seal in the

liquid line in the event of a power failure. A power failure may prevent the expansion valve

from closing completely by removing power before the valve steps all the way closed.

16 OM AGSD-1

Figure 6, AGS-D Piping Schematic

LIQUID

SHUT-OFF

VALVE

ELECTRONIC

EXPANSION

VALVE

SUCTION

TUBING

AIR

FLOW

AIR

FLOW

AIR

FLOW

CONDENSER

ASSEMBLY

SCHRADER

VALVE

(HEADER)

ECONOMIZER

FLOW

OUTSIDE AIR

TEMPERATURE

(WAA)

RELIEF

VALVE

DISCHARGE

TUBING

SCHRADER

VALVE

DISCHARGE

TRANSDUCER

(WH1, WH2)

DISCHARGE

TEMP. SENSOR

(WD1, WD2)

DISCHARGE

CHECK VALVE

SUCTION

TRANSDUCER

(WL1, WL2)

SUCTION

TEMP. SENSOR

(ST1, ST2)

SOLENOID

VALVE

THERMAL

EXPANSION

VALVE

SCHRADER

VALVE

SCHRADER

VALVE

ECONOMIZER FLASH GAS TO COMPRESSOR INTERSTAGE

WATER INWATER OUT

DX EVAPORATOR

(WOE TEMP.

SENSOR)

LIQUID

TUBING

SOLENOID

VALVE

CHARGING

VALVE

SIGHT

GLASS

OIL

SEPARATOR

SCHRADER

VALVE

SCHRADER

VALVE

(WIE TEMP.

SENSOR)

FIELD

CONNECTION

POINT

FIELD PIPING

SHOWN DASHED

STUB

TUBE

SCHRADER

VALVE

FIELD

CONNECTION

POINT

SUCTION

SHUT-OFF

KING VALVE

RELIEF

VALVE

SCHRADER

VALVE

CHARGING

VALVE

CHARGING

VALVE

STUB

TUBE

FILTER

DRIER #1

FILTER

DRIER #2

FIELD INSTALLED LIQUID LINE COMPONENTS

(

NOTE: FILTER DRIER #2 REQUIRED IN FIELD PIPING

)

SHUT-OFF

BALL VALVE

SCHRADER

VALVE

(MOUNTED ON SUCTION VALVE

BODY AT BACK SEAT PORT)

(MOUNTED ON SUCTION

VALVE BODY)

IMPORTANT:

THESE TWO COMPONENTS

MUST BE MOUNTED NEAR

REMOTE EVAPORATOR

COMPRESSOR

OIL FILTER

FRAME 4

COMPRESSOR

OIL

TRANSDUCER

(WO1, WO2)

CHARGING

VALVE

SHUT-OFF

VALVE

SIGHT

GLASS

CHECK

VALVE

FROM

OIL SEPARATOR

SHUT-OFF VALVE

COMPRESSOR

OIL SUPPLY

SCHRADER

VALVE

NOTE: The above figure illustrates the piping for the remote evaporator option. For the standard packaged

version, the field piping shown as dotted would be installed in the factory.

OM AGSD-1 17

Controller Operation

CP1 Inputs/Outputs

I/O for the unit control and for circuits one and two are found on CP1.

Analog Inputs

# Description Signal Source Normal Range

1 Slide Load Indicator #1 4-20 mA Current 1 to 23 mA

2 Slide Load Indicator #2 4-20 mA Current 1 to 23 mA

3 Evaporator Pressure #1 4-20 mA Current 3 to 22 mA

4 Discharge Temperature #1 PT1000 Sensor -45 to 240°F

5 Discharge Temperature #2 PT1000 Sensor -45 to 240°F

6 Condenser Pressure #1 4-20 mA Current 3 to 22 mA

7 Condenser Pressure #2 4-20 mA Current 3 to 22 mA

8 Evaporator Pressure #2 4-20 mA Current 3 to 22 mA

9 Evaporator Entering Water Temp NTC Thermister -45 to 212°F

10 Evaporator Leaving Water Temp NTC Thermister -45 to 212°F

Analog Outputs

# Description Output Signal Range

1 VFD #1 0-10VDC 0 to 100% (1000 steps resolution)

2 EXV #1 0-10VDC 0 to 6386 steps (1000 steps resolution)

3 VFD #2 0-10VDC 0 to 100% (1000 steps resolution)

4 EXV #2 0-10VDC 0 to 6386 steps (1000 steps resolution)

5 Reserved for Ceechina VFD#1 (future) 0-10VDC 0 to 100% (1000 steps resolution)

6 Reserved for Ceechina VFD#2 (future) 0-10VDC 0 to 100% (1000 steps resolution)

Digital Inputs

# Description Signal Off Signal On

1 Circuit Switch #1 Cir 1 disabled Cir 1 enabled

2 Circuit Switch #2 Cir 2 disabled Cir 2 enabled

3 Evaporator Water Flow Switch No Flow Flow

4 PVM/GFP #1 Fault No Fault

5 Mode Switch Cool mode Ice mode

6 Mechanical High Pressure Switch #1 Fault No Fault

7 Mechanical High Pressure Switch #2 Fault No Fault

8 Open

9 Open

10 VFD Fault #1 Fault No Fault

11 VFD Fault #2 Fault No Fault

12 Starter Fault #1 Fault No Fault

13H Low Pressure Switch #1 Fault No Fault

14H Low Pressure Switch #2 Fault No Fault

15 Starter Fault #2 Fault No Fault

16 Unit Switch Unit disabled Unit enabled

17 Remote Switch Unit disabled Unit enabled

18 PVM/GFP #2 Fault No Fault

18 OM AGSD-1

Digital Outputs

# Description Output OFF Output ON

1 SSS Enable Compressor Off Compressor On

2 SV Load Off Load

3 SV Unload Off Unload

4 Open

5 SV Liquid Line Off Enabled

6 Fan motor 11/VFD enable Off Fan on

7 Fan motor 12 Off Fan on

8 Fan motor 13/14 Off Fans on

9 SSS Enable Compressor Off Compressor On

10 SV Load Off Load

11 SV Unload Off Unload

12 EXV close #1 Open Pumpdown

13 EXV close #2 Open Pumpdown

14 Open

15 SV Liquid Line Off Fans on

16 Fan motor 21/VFD enable Off Fans on

17 Fan motor 22 Off Fans on

18 Fan motor 23/24 Off Fans on

Expansion I/O Controller 1

EXB1 is connected to CP1 for additional I/O.

Analog Inputs

# Description Signal Source Expected Range

1 Suction Temperature #1 NTC Thermister -45 to 195°F

2 Suction Temperature #2 NTC Thermister -45 to 195°F

3 Ambient Temperature NTC Thermister -45 to 195°F

4 Open

Analog Outputs

# Description Output Signal Range

1 Open

Digital Inputs

# Description Signal Off Signal On

1 Thermistor Fault #1 Fault No fault

2 Thermistor Fault #2 Fault No fault

3 Open

4 Open

Digital Outputs

# Description Output Off Output On

1 Evap Water Pump Output #1 Pump Off Pump On

2 Remote Alarm Bell Alarm Off Alarm On

3 SV Economizer #1 Off Enabled

4 SV Economizer #2 Off Enabled

OM AGSD-1 19

Expansion I/O Controller 4

EXB4 is connected to CP1 for additional I/O.

Analog Inputs

# Description Signal Source Expected Range

1 Chilled Water Reset 4-20 mA Current 4 to 20 mA

2 Demand Limit 4-20 mA Current 4 to 20 mA

3 Oil Pressure #1 4-20 mA Current 3 to 22 mA

4 Oil Pressure #2 4-20 mA Current 3 to 22 mA

Analog Outputs

# Description Output Signal Range

1 Open

Digital Inputs

# Description Signal Off Signal On

1 Open

2 External Alarm Alarm active Alarm not active

3 Open

4 Open

Digital Outputs

# Description Output Off Output On

1 Fan motor 15/16 Fans Off Fans On

2 Fan motor 17/18/19 Fans Off Fans On

3 Fan motor 25/26 Fans Off Fans On

4 Fan motor 27/28/29 Fans Off Fans On

Expansion I/O Controller 3

EXB3 is connected to CP1 for additional I/O.

Analog Inputs

# Description Signal Source Range

1 Open

2 Open

3 Open

4 Open

Analog Outputs

# Description Output Signal Range

1 Open

Digital Inputs

# Description Signal Off Signal On

1 Pump #1 alarm Pump Failure Pump OK

2 Pump #2 alarm Pump Failure Pump OK

3 Open

4 Open

Digital Outputs

# Description Output Off Output On

1 Evap Water Pump Output #2 Pump Off Pump On

2 Compressor Status Enable #1 Compressor Off Compressor On

3 Compressor Status Enable #2 Compressor Off Compressor On

4 Compressor Status Enable #3 Compressor Off Compressor On

20 OM AGSD-1

Controller CP2

I/O for circuit three (applies to AG S330D to 450D) are found on CP2.

Analog Inputs

# Description Signal Source Normal Range

1 Slide Load Indicator #3 4-20 mA Current 1 to 23 mA

2 Open

3 Suction Pressure #3 4-20 mA Current 3 to 22 mA

4 Discharge Temperature #3 PT1000 Sensor -45 to 240°F

5 Open

6 Discharge Pressure #3 4-20 mA Current 3 to 22 mA

7 Open

8 Open

9 Open

10 Open

Analog Outputs

# Description Output Signal Range

1 VFD #3 0-10VDC 0 to 100% (1000 steps resolution)

2 EXV #3 0-10VDC 0 to 6386 steps (1000 steps resolution)

3 Open

4 Open

5 Open

6 Open

Digital Inputs

# Description Signal Off Signal On

1 Circuit Switch #3 Cir 3 disabled Cir 3 enabled

2 Open

3 Open

4 PVM/GFP #3 Fault No Fault

5 Open mode Ice mode

6 Mechanical High Pressure Switch #3 Fault No Fault

7 Open

8 Open

9 Open

10 VFD Fault #3 Fault No Fault

11 Open No Fault

12 Starter Fault #3 Fault No Fault

13 Open

14H Low Pressure Switch #3 Fault No Fault

15 Open

16 Open

17 Open

18 Open

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McQuay AGS 450D Operating instructions

Brand: McQuay

Model: AGS 450D

Type: Operating instructions

This manual is also suitable for

AGS 225D

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McQuay AGS 450D Operating instructions

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McQuay AGS 450D Operating instructions

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