n. Controlled Compressor Shutdown:
The controls shall be capable of being configured to soft stop the compressor. The display shall indicate “shutdown in progress.”
a. Unit shall automatically shut down when any of the following conditions occur (each of these protective limits shall require manual reset and cause an alarm message to be displayed on the control panel screen, informing the operator of the shutdown cause):
1) Motor overcurrent
2) Over voltage*
3) Under voltage*
4) Single cycle dropout*
5) Low oil sump temperature
6) Low evaporator refrigerant temperature
7) High condenser pressure
8) High motor temperature
9) High compressor discharge temperature
10) Low oil pressure
11) Prolonged stall
12) Loss of cooler water flow
13) Loss of condenser water flow
14) Variable frequency drive fault
15) High variable frequency drive temperature
* Shall not require manual reset or cause an alarm if auto-restart after power failure is enabled.
b. The control system shall detect conditions that approach protective limits and take self-corrective action prior to an alarm occurring. The system shall automatically reduce chiller capacity when any of the following parameters are outside their normal operating range:
1) High condenser pressure
2) High motor temperature
3) Low evaporator refrigerant temperature
4) High motor amps
5) High VFD rectifier temperature
6) High VFD inverter temperature
c. During the capacity override period, a pre-alarm (alert) message shall be displayed informing the operator which condition is causing the capacity override. Once the condition is again within acceptable limits, the override condition shall be terminated and the chiller shall revert to normal chilled water control. If during either condition the protective limit is reached, the chiller shall shut down and a message shall be displayed informing the operator which condition caused the shutdown and alarm.
d.Internal built in safeties shall protect the chiller from loss of water flow. Differential pressure switches shall not be allowed to be the only form of freeze protection.
3. Diagnostics and Service:
a. A self diagnostic controls test shall be an integral part of the control system to allow quick identification of malfunctioning components.
b. Once the controls test has been initiated, all pressure and temperature sensors shall be checked to ensure they are within normal operating range. A pump test shall automatically energize the chilled water pump, condenser water pump, and oil pump. The control system shall confirm that water flow and oil pressure have been established and require operator confirmation before proceeding to the next test.
c. In addition to the automated controls test, the controls shall provide a manual test which permits selection and testing of individual control components and