38
Table 5 - Protective limits and control settings (continued)
MONITORED PARAMETER
ALARM/ALERT LIMIT
COMMENTS
Starts Limit Exceeded
100
More than 8 starts in 12 hours
Preset Prestart Alert
Low Chilled Water Flow
229
CHILLED LIQUID FLOW = FALSE after CHILLED
WATER PUMP = ON & WATER FLOW VERIFY TIME
elapsed
Optional Alarm, Configure WATER FLOW VERIFY TIME
in SETUP1 screen
Low Cond Water Flow
230
COND WATER FLOW = FALSE after COND WATER
PUMP = ON & WATER FLOW VERIFY TIME elapsed
Optional Alarm, Configure WATER FLOW VERIFY TIME
in SETUP1 screen
High Approach - Evaporator
162
EVAPORATOR APPROACH > EVAP APPROACH
ALERT and startup complete
Configure EVAP APPROACH ALERT in SETUP1 screen
Condenser
163
CONDENSER APPROACH > COND APPROACH
ALERT and startup complete
Configure COND APPROACH ALERT in SETUP1
screen
VFD - High VFD Speed
245
ACTUAL VFD SPEED > VFD SPEED 10% Preset Alarm, Must be o10% threshold for 75
seconds
Failure to Stop
204
PERCENT LOAD CURRENT >15% and VFDSTART =
NO for 20 seconds
Preset Alarm, PERCENT LOAD CURRENT = AVERAGE
LOAD CURRENT/MOTOR RATED LOAD AMPS
Rectifier - High Temperature
218
RECTIFIER TEMPERATURE limit exceeded
Preset Alarm, Configure RECTIFIER TEMP OVERRIDE
in SETUP1 screen
110
RECTIFIER TEMPERATURE > RECTIFIER TEMP
OVERRIDE – 11.1 K)
Prestart Alert, Configure RECTIFIER TEMP OVERRIDE
in SETUP1 screen
Overcurrent
241
Rectifier current limit exceeded
Preset Alarm
Power Fault
200
IGBT current limit exceeded or a fault was detected in
the rectifier
Preset Alarm
Inverter - High Temperature
219
INVERTER TEMPERATURE limit exceeded
Preset Alarm, Configure INVERTER TEMP OVERRIDE
in SETUP1 screen
111
INVERTER TEMPERATURE > INVERTER TEMP
OVERRIDE –11.1 K
Prestart Alert, Configure INVERTER TEMP OVERRIDE
in SETUP1 screen
286
Inverter current limit exceeded
Preset Alarm
Power Fault
201
IGBT current limit exceeded
Preset Alarm
Inductor - Overtemperature Switch 256
Inductor temperature limit exceeded
Preset Alarm, Temperature switch in reactor has opened
DC Bus Voltage - High
205/166
DC BUS VOLTAGE Limit Exceeded
Preset Alarm/Alert
Low
215
DC BUS VOLTAGE < 407 V d.c. at 400/480 V Line
Side Voltage
Preset Alarm
Ground Fault
220
GROUND FAULT CURRENT > 7% of Drive Rated
Amps Sensed
Preset Alarm
Optional Limits - Spare
Temperature
158,159,248,249 SPARE TEMPERATURE > SPARE TEMP LIMIT
Optional Alarm/Alert, Configure SPARE TEMP ENABLE
and SPARE TEMP LIMIT in SETUP1 screen
Guide Vane Position
253
ACTUAL GUIDE VANE POS > 4% after 4 minutes of
closing
Preset Alarm
ACTUAL GUIDE VANE POSITION < 0.045 V after
startup complete
Preset Alarm
ACTUAL GUIDE VANE POSITION > 3.15 V after
startup complete
Preset Alarm
ACTUAL GUIDE VANE POSITION < –1% after startup
complete
Preset Alarm
ACTUAL GUIDE VANE POSITION > 103% after
startup complete
Preset Alarm
Low Discharge Superheat
240
DISCHARGE SUPERHEAT < SUPERHEAT
REQUIRED –1.7 K for 60 seconds
Preset Alarm, DISCHARGE SUPERHEAT = COMP
DISCHARGE TEMP – CONDENSER REFRIG TEMP
Humidity - Dew Prevention
255
VFD COOLANT FLOW = 0% and VFD COLD PLATE
TEMPERATURE < T de 0.3 K or VFD
COOLANT FLOW = 0% and there is a Rectifier
Overtemperature or Inverter Overtemperature Alarm
Preset Alarm
Sensor Fault
168
HUMIDITY SENSOR INPUT > 4.5 V or HUMIDITY
SENSOR INPUT < 0.5 V
Preset Alert
5.7 - Ramp loading control
The ramp loading control slows down the rate at which the
compressor loads up. This control can prevent the com-
pressor from loading up during the short period of time
when the chiller is started and the chilled water loop
temperature has to be brought down to the CONTROL
POINT. This helps reduce electrical demand charges by
slowly bringing the chilled water to CONTROL POINT.
However, the total power draw during this period remains
almost unchanged.
There are several methods of ramp loading with the PIC III.
Ramp loading can be based on
LEAVING CHILLED
WATER, ENTERING CHILLED WATER, PERCENT
LINE CURENT,or PERCENT MOTOR KILOWATTS.
PULLDOWN RAMP TYPE is selected from the RAMP_
_DEM screen.
1.
temperature ramp loading
(TEMP PULLDOWN
DEG/MIN) limits the rate at which either
LEAVING
CHILLED WATER
or
ENTERING CHILLED
WATER
temperature decreases by an operator-
configured rate from the TEMP_CTL screen.
NOTE: If chiller control power has been off for 3 hours or
more, the next start-up (only) will follow temperature ramp
loading using the minimum rate regardless of the ramp
loading method and rate which are configured in the screens.
This is used to maximise oil reclaim during start-up.
.
Motor load ramp loading
(AMPS OR KW RAMP %/
MIN) limits the rate at which the compressor motor
current or compressor motor load increases. The
AMPS OR KW RAMP %/MIN rate is configured by
the operator on the RAMP_DEM screen in line
current or motor kilowatts.