Sequence of Operation
This section will acquaint the operator with the control logic of the Fast-
Pak™ control system. Be sure to refer to wiring diagrams at the end of this
manual when reviewing these step-by-step electrical sequences of opera-
tion.
Note:
Refer to the latest revision of CVHE-M-7 for a description of typical
mechanical operation. Refer to Sequence and Timing Functions on the fol-
lowing page for start-run-shutdown sequence and timing functions.
With the unit in auto, the FastPak panel checks compressor motor winding
temperature, and a minimum 30 second delay is initiated if the winding
temperature is less than 165° F. If it is greater than 165° F, however, a 15
minute delay period begins. The chilled water pump relay is energized and
evaporator water flow is proven.
Next, the FastPak panel checks the leaving evaporator water temperature
and compares it to the chilled water setpoint. If the difference between
these values is less than the start differential setpoint, cooling is not
needed.
If the FastPak panel determines that the difference between the evaporator
leaving water temperature and chilled water setpoint exceeds the start dif-
ferential setpoint, the unit enters the Initiate Start Mode and the oil pump
and the condenser water pump are started.
If condenser water flow is not proven (i.e. flow switch 5S2 does not close)
within 4.25 minutes, the unit is locked out on an MMR diagnostic.
Oil pressure must be verified within an adjustable time period or an MMR
diagnostic is generated.
When less than 5 seconds remain on the restart inhibit, the pre-start starter
test is conducted on Wye-Delta starters (if optional Starter module is in-
stalled and contactors are controlled directly). If faults are detected, the
unit’s compressor will not start and a MMR diagnostic will be generated.
After the pre-start starter test, the FastPak panel sends a start signal to the
compressor starter. Within 2 seconds, current must be detected. If there is
no current, a diagnostic will be called out. Proof of transition must occur
within 2.5 seconds of transition initiation, or startup is aborted and the unit
goes into the post lube mode and a diagnostic is generated.
If the compressor motor starts successfully, “Unit is Running” appears on
the display. At this time the purge unit will start operating on automatic and
will continue running as long as the chiller compressor is running.
Whenever the FastPak panel detects an MMR diagnostic condition, unit
operation is locked out and manual reset is required before the startup se-
quence can begin again. If the fault condition has not cleared, the FastPak
will not permit restart.
CVRC-M-1D
23
Operation - Chiller Control System
Содержание CVRC-M-1D
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