Unit Shutoff Ð To shut unit off, move LOCAL/ENABLE-
Complete Unit Stoppage Ð Complete unit stoppage can be caused by any of the following conditions:
1. | Cooling load satis®ed |
2. | Remote on/off contacts open |
3. | Programmed schedule |
4. | Emergency stop command from CCN |
5. | General power failure |
6. | Blown fuse in control power feed disconnect |
7. | Open control circuit fuse |
If stoppage occurs more than once as a result of any of the above safety devices, determine and correct the cause before attempting another restart.
Restart Procedure Ð After cause for stoppage has been corrected, restart is either automatic or manual, depending on fault. Manual reset requires that LOCAL/ENABLE-
Table 15 Ð Typical Stoppage Faults and Reset Types
8. | |
| position |
9. | Freeze protection trip |
10. | Low ¯ow protection trip |
11. Open contacts in chilled water ¯ow switch (optional) | |
12. | Open contacts in any auxiliary interlock. Terminals that |
| are jumpered from factory are in series with control switch. |
| Opening the circuit between these terminals places unit |
| in stop mode, similar to moving the control switch to |
| STOP position. Unit cannot start if these contacts are |
| open. If they open while unit is running, unit pumps down |
Chilled Fluid, Low Flow Chilled Fluid, Low Temperature
Chilled Fluid Pump Interlock
Control Circuit Fuse Blown
Low Refrigerant Pressure
Low Oil Pressure
Discharge Gas Thermostat Open
Manual reset
Auto reset ®rst time, manual if repeated in same day
Manual reset
Unit restarts automatically when power is restored
Manual reset
Auto reset ®rst time, then manual if within same day
Manual reset Manual reset
| and stops. |
13. | Cooler entering or leaving ¯uid thermistor failure |
14. | Low transducer supply voltage |
15. | Loss of communications between processor module and |
| other control modules |
16. | Low refrigerant pressure |
17. |
Single Circuit Stoppage Ð Single circuit stoppage can be caused by the following:
1.Low oil pressure in lead compressor
2.Open contacts in lead compressor
3.Low refrigerant pressure
4.Thermistor failure
5.Transducer failure
6.Ground fault in lead compressor indicator (indicator is
7.High suction superheat
8.Low suction superheat
9.Lead compressor circuit breaker trip. Stoppage of one circuit by a safety device action does not affect other circuit. When a safety device trips on a lead compres- sor, circuit is shut down immediately and EXV closes.
10.Ground fault for any circuit compressor
Lag Compressor Stoppage Ð Lag compressor stop- page can be caused by the following:
1.Open contacts in
2.Compressor ground fault (indicator is
3.Compressor circuit breaker trip
4.Not required to run to meet cooling load requirement
POWER FAILURE EXTERNAL TO THE UNIT Ð Unit restarts automatically when power is restored.
Alarms and Alerts Ð These are warnings of abnormal or fault conditions, and may cause either one circuit or the whole unit to shut down. They are assigned code numbers as described below. These code numbers are displayed
on the HSIO when the 
subfunction is entered. A
fault that affects one one circuit of the chiller will generate an alert, and a fault that affects the entire unit will generate an alarm.
Following is a detailed description of each alarm and alert code error and possible cause. Manual reset is accomplished by moving
Code 0 No alarms or alerts exist Codes 1 - 8 Compressor failure
If
If lead compressor in a circuit shuts down, the other com- pressors in the circuit stop and lock off. Only the alert mode for lead compressor is displayed.
The microprocessor is also programmed to indicate com- pressor failure if feedback terminal on
NOTE: It takes 5 seconds for the control to generate the alarm code and lock out the compressor(s) on compressor failure code(s) 1 through 8.
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