Operating Manual
OM AGSD-4
Group: Chiller
Part Number: 331375401
Date: May 2008
Supercedes: OM AGSD-3
Air-Cooled Screw Compressor Chiller
AGS 225D through AGS 450D
Software Version AGSG30101G/H
60 Hertz, R-134a
2 OM AGSD-4
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
...............................................................31
Quiet Night Sound Reduction............... 33
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
ON
M
ARK and
L
ON
W
ORKS
from Echelon
Corporation; Modbus from Gould, Inc.; McQuay and MicroTech II from McQuay International.
Unit controllers are L
ON
M
ARK
certified with an optional
L
ON
W
ORKS
communications module
Manufactured in an
ISO Certified facility
OM AGSD-4 3
This manual provides setup, operating, and troubleshooting information for the McQuay
MicroTech ΙΙ 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 AGSG30101G and H.
Version G contains the above changes and Version H only corrects an EXV bug and does
not change this manual’s content. 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: 3.01
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 ΙΙ 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-4
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
ON
W
ORKS
,
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-4 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-4
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-4 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
loading.
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.
ms
Milli-second
Maximum Saturated Condenser Temperature
The maximum saturated condenser temperature allowed is calculated based on the
compressor operational envelope.
8 OM AGSD-4
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.
SP
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-4 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
ALARM
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-4
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
4X20LC
D
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-4 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
Yes
Yes
No
No
Unit power up
Unit in Off state
No
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-4
Is more capacity
needed to satisfy load?
Has the stage up time
delay expired?
Start next circuit.
Yes
No
Load/unload as needed to
satisfy load.
Yes
No
Load/unload as needed to
satisfy load.
Can less circuits handle
the load?
Yes
Shut down one circuit.
No
Load/unload as needed to
satisfy load.
Is load satisfied?
No
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-4 13
Figure 5, Circuit Sequence of Operation
Next on?
Next off?
Start Compressor
Stage down now?
Pumpdown circuit
Yes
Yes
Yes
No
No
Unit power up
Circuit is in Off state
No
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
No
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
is
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
be
Off:Pumpdown Switch
.
14 OM AGSD-4
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 unit 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.
OM AGSD-4 15
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.
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-4
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
VALVEDISCHARGE
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
TO
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-4 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-4
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-4 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-4
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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