Standard Screw Compressor - RWB Series
3-4
M&M
R
EFRIGERATION
I
NC
.
allowed to start. If the slide valve position does not move below 5% within 5 minuets, the
compressor will be failed on START SLIDE POSITION. Once the motor starts, the slide valve
position is monitored while the compressor is coming up to speed. If the slide valve position
increases to above 10% during this time, the compressor will be failed on START SLIDE
POSITION also
The oil pressure is checked at all times to assure it is above the OEM minimum (20 PSID for
Full Lube, and 10 PSID for Cycling and Pre-lube) at all times. If the oil pressure drops below
this setting within the first two minutes of operation, this compressor will be failed on OEM
START OIL PRESS LOW.
The sequence for starting the compressor varies based on the Lubrication System configura-
tion as described below:
1. The oil pump is started.
2. The oil pressure must rise above the OEM start oil pressure setpoint and maintain
that pressure for at least 6 seconds. For pre-lube and cycling oil pumps the OEM
start oil pressure setpoint is 5 PSIG. For a full lube oil pump the OEM start oil pres-
sure is 20 PSIG. If the oil pressure fails to exceed these limits within 2 minutes the
start sequence fails on OEM START OIL PRESS LOW.
3. The slide valve is unloaded and must move below 5% before the compressor can
start. If the slide valve does not respond within 2 minutes the start sequence is failed
on START SLIDE POSITION. Unloading is continued while the compressor is start-
ing to assure that the slide valve does not load.
4. The Vi slide stop is decreased to the low Vi position for compressor start.
5. Once the above conditions are met the motor is started and the anti-cycle timer
begins counting.
6. After the motor starts, checks on the oil pressure are delayed for six (6) seconds.
After this initial delay the oil pressure is checked to assure that it remains above the
OEM start oil pressure setpoint ( 5 PSIG for pre-lube and cycling oil pumps and 20
PSIG for full-lube lube oil pumps ).
7. The oil pressure is also checked to assure that it exceeds the OEM transition to run
setpoint. For full-lube oil pumps the setpoint remains 20 PSIG. For cycling or pre-
lube pumps the setpoint is 55 PSIG. If the oil pressure fails to reach these values
within the 2 minute maximum start delay the compressor is failed on START OIL
PRESS LOW.
8. Once all of the above criteria have been achieved the screw compressor will transi-
tion into the running state where capacity control can be performed.
The screw compressor can be started manually, automatically, or remotely based on the oper-
ating mode chosen. The compressor will not start in any mode if a failure condition exists.
Manual Mode
Manual Start is accomplished by selecting the START hot key and answering yes to the
start confirmation screen. A manual start is used in Manual mode, Local mode, or Auto-
matic mode when automatic Start/Stop is disabled.
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