Thermo King CRR-20, Руководство по обслуживанию

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4-12 Sequence of Operation
µ
P-D Controller
CRR-20 & CRR-40, September 1999
Chill Loads Frozen Loads
Setpoints at -9.9 C Setpoints at -10.0 C
(14.4 F) and Above (14.0 F) and Below
Cool Mod Null Heat Defr Cool Null Defr Unit Function
• • • •
Evaporator Fans HIGH SPEED1
• •
Evaporator Fans LOW SPEED1
• •
Evaporator Fans OFF1
• • • •
Proportional-integral Derivative (Supply Air) Control
• •
Return Air Sensor Control
• •
Evaporator Coil Sensor Control
• • •
Compressor ON2
• • •
Liquid Line Solenoid Valve OPEN (energized)
• • • • •
Condenser Fan ON3
• •
KVQ Valve OPEN (valve de-energized)4
• • •
KVQ Valve MODULATING (valve energized)4
• • •
Electric Heaters ON (energized)
1Return air temperature determines the evaporator fan speed (except when Economy Mode is ON):
• At return air temperatures of -9.9 C (14.4 F) and above, the evaporator fans operate on high speed.
• At return air temperatures of -10.0 C (14.0 F) and below, the evaporator fans operate on low speed.
2Null Mode: • On Chill Loads, the compressor stays ON for 60 seconds to pump down the low side.
• On Frozen Loads, the compressor stays ON for 30 seconds to pump down the low side.
3Condenser fan is ON when the condenser pressure is above 1380 +/- 50 kPa, 13.80 +/- 0.5 bar, 200 +/- 7 psig.
• Null Mode: If the condenser fan was ON when the unit shifted to NULL, it will operate for 30 seconds and stop.
• Water-cooled Condenser Option: When water supply pressure opens the water pressure switch, the controller stops the con-
denser fan.
• Controller set to unit configurations 5015 or 5016 (CRR-40-52 units): The controller uses the compressor and/or condenser
temperature to cycle the condenser fan between ON and OFF.
4KVQ valve MODULATES:
• When the Power Limit mode is ON.
• When the calculated temperature differential is less than 10 C (17.9 F) above setpoint.
NOTE: Controller OPENS (energizes) the liquid injection valve when the compressor is ON only if the com-
pressor discharge temperature exceeds 138 C (280 F).
Operating Mode Function Chart — Standard Operation