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Related Manuals for McQuay AGS 230A' AGS 230B
Summary of Contents for McQuay AGS 230A' AGS 230B
- Page 1 Operation Manual OM AGSB-5 Group: Chiller Part Number: 331373201 Date: June 2005 Supersedes: OM AGSB-4 GeneSys ™ Air-Cooled Screw Compressor Chiller AGS 230A/B through AGS 475A/B, 60 Hertz AGS 206A/B through AGS 411A/B, 50 Hertz Software Version AGSU30101H...
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Page 2: Table Of Contents
Manufactured in an ISO Certified facility "McQuay" is a registered trademark of McQuay International, Information 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. - Page 3 MicroTech ΙΙ™ controller for Model AGS-B vintage, air-cooled rotary screw compressor chillers. Please refer to the current version of IMM AGSB (available from the local McQuay sales office or on www.mcquay.com) for information relating to the solid state starters and to the unit itself.
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Page 4: Microtech Ii™ Features
®, Building Automation System (BAS) communication capability via L ORKS Modbus®, or BACnet® standard protocols for all BAS manufacturers-simplified with McQuay’s Protocol Selectability™ feature. • Service Test mode for troubleshooting controller hardware. • 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. -
Page 5: General Description
General Description General Description The AGS MicroTech ΙΙ distributed control system consists of multiple microprocessor- based controllers that provide monitoring and control functions required for the controlled, efficient operation of the chiller. The system consists of the following components: • Unit Controller, one per chiller −... -
Page 6: Component Description
Component Description Unit and Circuit Controller Description Terminology and Definitions Accumulator The accumulator is an electronic “bank” that stores information relative to fan operation and fan capacity required. It is the heart of the controller’s fuzzy logic feature. Various events such as cooling load changes and ambient air temperature changes, add or subtract points in the bank. - Page 7 EvapRecTimer The evaporator recirculation timer establishes the length of time the chilled water pump will run after the controller receives an enable signal and the Wait for Flow timer time out. This period allows time for the chilled water to circulate sufficiently to determine if there is a need for cooling.
- Page 8 Slide Target, Slide Position See page 14 for explanation of these terms. Setpoint 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...
- Page 9 Each chiller has one unit controller and a circuit controller for each compressor circuit (two or three depending on unit size). The controllers are connected and communicate via a pLAN (local area network). The circuit controllers communicate with, and control the operation of, the compressor's solid state starter and the circuit electronic expansion valve (EXV).
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Page 10: Control Operation
Control Operation This section on MicroTech II control is divided into four subsections: • Circuit Controller, explains the functions of the circuit controller, see page 10. • Unit Controller, explains the functions of the unit controller, see page 24. • Using the Controller, explains how to navigate through the menus and how to make entries, see page 37. -
Page 11: Setpoints
Table 4, Digital Outputs Description Load Output OFF Output ON Voltage Compressor Starter Contact Relay Compressor off Compressor on M1 Contactor (fan 1) Contactor Coil Fans off Fans on M2 Contactor (fan 2) Contactor Coil Fans off Fans on M3 Contactor (fan 3) Contactor Coil Fans off Fans on... - Page 12 Table 5, Circuit Controller Setpoints Description Default Range Compressor Circuit mode Enable Disable, Enable, Test Slide control Auto Auto, Manual Slide position 0-100% Compressor Size 205,220,235 Clear Cycle Timers No, Yes Maximum Slide Target 100.0 0-100.0% EXV control Auto Auto, Manual Manual EXV position 0-6386 Pre-open timer...
- Page 13 Circuit Operating Mode The circuits on the chiller can each be individually enable or disabled. Test mode on each circuit can also be entered independent of the all other circuits. With the circuit switch on, the circuit mode setpoint offers settings of either Enable or Disable. This simply allows the circuit to be disabled through a keypad setting.
- Page 14 Slide Calibration Procedure The slide is calibrated in the factory before shipment but may have to be recalibrated in the field, especially if relevant slide parts have been replaced. Slide Position is a relative capacity adjustment from 0.0%(Min load) to 100.0%(Max Load). There are two MicroTech II controller readings that apply to the indicator, Slide Target and Slide Position.
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Page 15: Compressor Control
Compressor Control Multiple Compressor Staging This section defines which compressor is the next one to start or stop. The next section defines when the start, or stop, is to occur. Functions 1. Can start/stop compressors according to an operator-defined sequence. 2. - Page 16 Stopping Staging down, at least two compressors running: For staging off compressors, the LWT must be less than the active LWT setpoint minus the Stage Delta-T. Based on default settings, the active setpoint would be 44°F, and stage delta of 2 degrees F. So the LWT must be less than 42°F to stage off a compressor. This is a sufficient condition to trigger a stage down.
- Page 17 High Condenser Pressure If the compressor is running and the condenser pressure rises above the High Lift Pressure Hold setpoint, the compressor will not be allowed to increase capacity. The slide position target will be limited to a maximum value equal to the target at the time the hold condition was triggered.
- Page 18 • Soft Load – (ON/OFF) • Begin Capacity Limit – (Unit %) • Soft Load Ramp – (seconds) The Soft Load Unit Limit increases linearly from the Begin Capacity Limit set-point to 100%, over the amount of time specified by the Soft Load Ramp set-point. If the option is turned off, the soft load limit is set to 100%.
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Page 19: Condenser Fan Control
Load/Unload Select The load/unload selector determines which solenoid will be pulsed for a change in capacity. When unloading is required, the load/unload select output should be off. When loading of the compressor is required, the output should be on. Slide Pulse The slide pulse output moves the compressor slide in order to reach the capacity reflected by the slide position target. - Page 20 Table 7, Staging with VFD Stage Fans On 1,2,3 1,2,3,4 1,2,4,5,6 1,2,3,4,5,6 1,2,3,5,6,7,8 1,2,3,4,5,6,7,8 Staging Up There are four stage-up deadbands that apply to the FanTrol stages. Stages one through three use their respective deadbands. Stage four to eight share the fourth stage-up deadband.
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Page 21: Exv Control
EXV Control Three different expansion valve (EXV) control modes are used. Any time the EXV is not in one of these control modes, it will be closed. For any of the control modes, the EXV position is limited to a range based on the slide position target. The minimum setting provides sufficient flow for motor cooling, the maximum flow limit helps prevent flood back to the compressor. - Page 22 The base pressure target is calculated using the following formula: Base target = 2/3LWT – 8 The base target is limited to a range from the low pressure inhibit setpoint, plus 2 psi, up to 52 psi. The pressure control target may be adjusted if the discharge superheat is not within an acceptable range.
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Page 23: Evaporator Oil Return Line Control
Closed Any time the EXV is not in pre-open, pressure control, or subcool control, it will be in a closed state. At this time, the EXV position is 0 steps and the EXV close signal is active. Manual EXV Control The EXV position can be set manually. -
Page 24: Unit Controller
Unit Controller Inputs/Outputs The following parameters are analog inputs to this controller. They are used internally as needed and are sent to the correct pLAN addresses for use by other controllers or displays. Table 10, Unit Analog Inputs Description Signal Source Range Outdoor Ambient Temperature Thermistor (10k@25°C) - Page 25 Table 13, Unit Controller Setpoints Description Default Range Unit Unit Enable OFF, ON COOL, COOL w/Glycol, Unit Mode COOL ICE w/Glycol, TEST Control source SWITCHES SWITCHES, KEYPAD, NETWORK COOL, COOL w/Glycol, COOL/ICE Available Modes COOL w/Glycol, ICE w/Glycol, TEST 25.0(40.0) to 60.0 °F Cool LWT 44.
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Page 26: Unit Enable
Automatic Adjusted Limits The following setpoint ranges will be adjusted based on selected options. Table 14, Evaporator Leaving Water Temperature Range Mode Range Unit Mode = Cool 40 to 60°F Unit Mode = Cool w/Glycol, Ice, Ice w/ Glycol 20 to 60°F Table 15, Evaporator Freeze Temperature Range Mode Range... -
Page 27: Unit Mode Selection
1. The Mode field is an informational display, showing the active control mode of the chiller. It is used as an input only when the source is set to keypad, only then can this field be changed manually. 2. The Source field has three options, “SWITCHES” (default), “KEYPAD”, and “BAS NETWORK”. - Page 28 SET UNIT SPs Available Modes = COOL Select w/Unit Swt Off The setpoint can be altered by the keypad, BAS, and Mode input. Changes to the Unit Mode Setpoint are controlled by two additional setpoints. • Control Source Setpoint: Determines the source that can change the Unit Mode Setpoint with options of KEYPAD (pCO ), NETWORK, or SWITCHES.
- Page 29 Circuit Controllers: Be sure the pumpdown switch is in the off position. Press the Menu button (the top far right button with three horizontal lines on it) on the circuit controller. Press the button that corresponds to “SET”, then press “COMPRESSOR SPs”. Now press the down arrow button once.
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Page 30: Evaporator Pump State Control
Evaporator Pump State Control The state-transition diagram shown below controls operation of the evaporator pump. Figure 4, Evaporator Pump Control Power ON [Unit State = AUTO AND NOT [OAT low AND LWT > 40 F LWT < Freeze sp – 1.0 F [Unit State=OFF AND LWT >... - Page 31 Reset is accomplished by changing the Active Leaving Water setpoint from the Cool LWT setpoint to the Cool LWT setpoint + Max Reset setpoint as the EWT – LWT (Evap Delta-T) varies from the Start Reset Delta-T setpoint to 0. Figure 5, Return Water Reset Conditions Return Reset Cool LWT+Max Reset...
- Page 32 Reset Type – Outside Air Temperature (OAT) The Active Leaving Water setpoint is reset based on the outdoor ambient temperature. Parameters used: 1. Cool LWT setpoint 2. Max Reset setpoint 3. OAT Reset is 0 if the outdoor ambient temperature is greater than 75°F. From 75 down to 60°F the reset varies linearly from no reset to the max reset at 60°F.
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Page 33: Alarms And Events
Alarms and Events Situations may arise that 1) require some action from the chiller, or that 2) should be logged for future reference. A condition that causes a shutdown and requires manual reset is known as a stop alarm. Other conditions can trigger what is known as an event, which may or may not require an action in response. - Page 34 Table 23, Circuit Stop Alarms Description Occurs When: Action Taken Start Aborted, Evap or Cond pressure< 7 psi when Compressor Start No Pressure at Start Circuit Locked Out Requested on Manual Reset [Freezestat trip OR Evaporator Press < 0 psi OR Low Low Evaporator Pressure Rapid Stop Pressure Sw Open] AND Compressor State = Run...
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Page 35: Alarm And Event Logging
Minimum Saturated Condenser Value If Sat Evap Temp < 35, then Min sat cond value = 73 If Sat Evap Temp >= 35 and < 55, then Min sat cond value = (6/5)(Sat Evap Temp – 35) + 73 If Sat Evap Temp >= 55 then Min sat cond value = 97 Circuit Events The following events do not cause compressor shutdown but limit operation of the circuit in... - Page 36 A separate alarm log stores the last 25 alarms to occur. When an alarm occurs, it is put into the first slot in the alarm log and all others are moved down one, dropping the last alarm. In the alarm log, the date and time the alarm occurred are stored, as well as a list of other parameters.
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Page 37: Using The Controller
Using the Controller 4x20 Display & Keypad Layout The 4-line by 20-character/line liquid crystal display and 6-key keypad for both the circuit controller and unit controller is shown below. MENU Key Figure 8, Display (in MENU mode) and Keypad Layout Left Arrow Key and Red Alarm Light Air Conditioning... - Page 38 When in the MENU mode (as shown in Figure 8), pressing the LEFT ARROW key will select the ALARM menus, the RIGHT ARROW key will select the VIEW menus and the UP key the SET menus. The controller will go the next lower menu in the hierarchy, and then other menus can be accessed by using the ARROW keys.
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Page 39: Security
5. Press the ENTER key to move the cursor down from the top line to the second line in order to make the change. 6. Use the ARROW keys (now in the edit mode as shown above) to change the setting. 7. -
Page 40: Unit Controller Menus
Unit Controller Menus Various menus are shown in the controller display. Each menu screen shows specific information. In some cases menus are used only to view status of the unit, in some cases they are used for checking alarms, and in some case they are used to set the setpoint values that can be changed. -
Page 41: Screen Definitions
Selection can then be made by using the LEFT/RIGHT keys to move between columns and the UP/DOWN keys to move between rows. The menu structure allows the return to the last screen viewed in each column. (This feature also applies to navigation using the function keys.) As an example: Attempts to scroll past the limits of the matrix are ignored. - Page 42 VIEW UNIT TEMP Evap LWT= XXX.X F Evap EWT= XXX.X F Active SP= XXX.X F VIEW UNIT TEMP LWT Pulldn= 0.0 F/m Evap Delta T=XX.X F Outdoor Air=XXX.X F NOTE: In the following VIEW CIRCUIT screens, the N field indicates which compressor (#1, #2, etc.) is being viewed.
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Page 43: Set Screen Definitions
VIEW REFRG CIR N (5) Evap Approach=XX.X°F Cond Approach=XX.X°F EXV position = XXXX VIEW FANS Fans On, Cir 1= 0 Fans On, Cir 2= 0 Fans On, Cir 3= 0 VIEW FANS VFD Cir 1= 000.0 % VFD Cir 2= 000.0 % VFD Cir 3= 000.0% ALARM and EVENT Screen Definitions The alarms and events shown are examples only. - Page 44 SET UNIT SPs Available Modes = COOL Select w/Unit Swt. Off SET UNIT SPs Cool LWT = XX.X°F Ice LWT – XX.X°F The unit will only use the setpoint for the Mode selected. SET UNIT SPs StartDelta= XX.X°F StopDelta= XX.X°F StageDelta= XX.X°F The StartDelta is the number of degrees above the chilled water setpoint the water temperature must rise for a compressor to start when no compressors are running.
- Page 45 SET UNIT SPs Demand Limit= Off Low Amb Lock = XX.X°F SET UNIT SPs Ice Time Delay=xxhrs Clear Ice Timer=No SET UNIT SPs (10) CLOCK dd/mmm/yyyy hh:mm:ss SET UNIT SPs (11) Units = °F/psi Lang = ENGLISH Inch-Pound units of measure and English language are the only options available in this software version.
- Page 46 SET COMP SPs # of Compressors=X Pumpdn press=XX.X psi Pumpdn time= XXX sec SET COMP SPs Light Load Stage Down Point=XX% slide Stage Dn Delay=XXmin SET COMP SPs Stg Up Delay= XXXsec SET ALARM LMTS Low Evap Pressure Hold=59.0 psi Unload=58.0 psi SET ALARM LIMITS (2) LowOilDelay= XXX sec...
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Page 47: Circuit Controller Menus
TEST Screen Definitions TEST UNIT Alarm Out=Off Evap Heaters=Off Pump1=Off Pump 2=Off Circuit Controller Menus See "Using the Controller" on page 37 for information on how to navigate and use the menu screens, as well as changing setpoints. As an alternate to selecting screens with the menu function, it is possible to scroll through all of them with the 4 arrow keys. - Page 48 VIEW CIR STATUS Off:Ready Slide Pos= XXX.X% Slide Target= XXX.X% VIEW CIR STATUS Hours = XXXXX Starts = XXXXX VIEW CIR STATUS Digital Outputs Output Number 1 2 3 4 5 6 7 8 9 10 Output Status 0 0 0 0 0 0 0 0 0 0 The digital outputs in menu 3 and 4 and the analog outputs in menu 5 are defined in Table 2 and Table 4 beginning on page 10.
- Page 49 VIEW REFRIGERANT Suct Temp = XXX.X °F Disc Temp = XXX.X °F Liq Temp = XXX.X °F VIEW REFRIGERANT XXX.X °F Suct SH = XXX.X °F Disc SH= Liquid SC= XXX.X °F VIEW REFRIGERANT Evap Approach=XX.X °F Cond Approach=XX.X °F VIEW REFRIGERANT MaxCondSatT=XXX.X°F EXV Control=Pressure...
- Page 50 SET COMP SPs Circuit Mode=Enable Slide Control=auto Slide Target= XXX.X% SET COMP SPs Oil return Max slide= XX.X% Min Disch SH=XX.X SET COMP SPs Motor FLA = NNNN amps Mptpr RLA = NNNN amps EXV Setpoints SET EXV SPs EXV Control=auto Manual EXV Pos=XXXX Pre-open time=XXX sec SET EXV SPs...
- Page 51 SET FAN SPs Cond Sat Temp Target Setpoint= XXX.X °F SET FAN SPs # Fans On At Startup >75°F >90°F >105°F Sensor Offsets SET SENSOR OFFSET (1) Evap Press= XX.X psi Cond Press= XX.X psi Liq Press= XX.X psi SET SENSOR OFFSET (2) Suct Temp= X.X F Disch Temp= X.X F Liq Temp= X.X F...
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Page 52: Sequence Of Operation
Sequence of Operation The following sequence of operation is typical for McQuay models AGS chillers. The sequence may vary depending on the software revision or various options that may be installed on the chiller. Off Conditions Power is supplied to each power panel located between condenser sections. Optionally, the power may be supplied to a single power connection located in a terminal box on the base of the unit. - Page 53 If the leaving chilled water temperature is above the Leaving Chilled Water Setpoint plus one-half of the Control Band 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.
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Page 54: Start-Up And Shutdown
Figure 10, AGS Piping Schematic FLOW CHECK RELIEF VALVE VALVE CHARGING VALVE SCHRADER DISCHARGE VALVE TUBING SCHRADER (EACH DISCH HEADER) SEPARATOR DISCHARGE TUBING ANGLE SIGHT VALVE CONDENSER CONDENSER GLASS ASSEMBLY ASSEMBLY SIGHT GLASS FLOW FLOW FLOW RELIEF VALVE (EVAP SHELL) TO REAR OF BUTTERFLY VALVE COMPRESSOR... -
Page 55: Expansion Valve Operation
5. Check to see that pumpdown switches PS1 and PS2 are in the "Pumpdown and Stop" (open) position. Throw the S1 switch to the "auto" position. 6. Under the "Control Mode" menu of the keypad, place the unit into the automatic cool mode. - Page 56 Subcool Control: After completing pressure control, the EXV transitions to subcool control, which is used only when the unit mode is Cool. In this mode, subcooling is controlled by the EXV, with adjustments to the subcool target based on discharge superheat. The base subcool target varies linearly from 9 to 20 F as slide position changes from 0 to 100%.
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Page 57: Extended (Seasonal) Shutdown
Start-up After Temporary Shutdown 1. Insure that the compressor heaters have been energized for at least 12 hours prior to starting the unit. 2. Start the chilled water pump. 3. With System switch S1 in the "on" position, move pumpdown switches PS1 and PS2 to the "auto"... -
Page 58: Evaporator Freeze Protection
7. Vent the air from the evaporator water side as well as from the system piping. Open all water flow valves and start the chilled water pump. Check all piping for leaks and recheck for air in the system. Verify the correct flow rate by taking the pressure drop across the evaporator and checking the pressure drop curves in the installation manual, IMM AGS. -
Page 59: Operating Limits
Operating Delta-T range, 6 degrees F to 16 degrees F (10.8 C to 28.8 C) Maximum operating inlet fluid temperature, 66°F (19°C) Maximum startup inlet fluid temperature, 90°F (32°C) Maximum non-operating inlet fluid temperature, 100°F (38°C) NOTE: Contact the local McQuay sales office for operation outside of these limits. OM AGSB-5... -
Page 60: Refrigerant Charging
Refrigerant Charging Why does the AGS flooded evaporator use subcooling control? Subcool control maintains proper evaporator level for efficiency and is the most stable value with which to control the flooded evaporator chiller. Discharge superheat control is affected by many variables such as motor heat, refrigerant flow, number of fans operating, amount of refrigerant in the oil, etc,. - Page 61 Basic Charging Information: Determine the following: 1. What control mode is the EXV in? 2. What is the circuit status? 3. What is the compressor slide position? 4. What is the DSH at 100%? 5. What is the suction pressure at 100%? 6.
- Page 62 Figure 11, Discharge Superheat vs. Pressure Lift Discharge Superheat vs. Pressure Lift 34/44 44/54 54/64 64/74 50.0 70.0 90.0 110.0 130.0 150.0 170.0 190.0 210.0 230.0 250.0 Pressure Lift(Discharge Pressure - Suction Pressure) Discharge superheat is directly related to the amount of liquid carried from the evaporator and amount of motor heat rejected into the refrigerant.
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Page 63: Bas Interface
• Send a description of each alarm when it occurs. Reference McQuay documents ED 15057 and ED 15062 may be obtained from the local McQuay sales office, from the local McQuayService office, or from the McQuay Technical Response Center, located in Staunton, Virginia (540-248-0711). -
Page 64: Field Wiring Diagram
Field Wiring Diagram Figure 12, Typical Field Wiring Diagram UNIT MAIN DISCONNECT TERMINAL BLOCK (BY OTHERS) GND LUG 3 PHASE TO COMPRESSOR(S) POWER AND FAN MOTORS SUPPLY FUSED CONTROL CIRCUIT TRANSFORMER 120 VAC NOTE: ALL FIELD WIRING TO BE TB1-2 INSTALLED AS NEC CLASS 1 (115 VAC) WIRING SYSTEM WITH CONDUCTOR... - Page 66 This document contains the most current product information as of this printing. For the most up-to- date product information, please go to www.mcquay.com. © 2004 McQuay International• (800) 432-1342 • OM AGSB-5 (6/05) www.mcquay.com...
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