26
OPERATING THEORY
OPERATING THEORY
1
Setpoint temperature and controlling mode
setting determine the evaporator fan speed:
Normal Operation :
Chill Loads — High
or low speed fans; Frozen Loads — Low speed
fans or no fans.
2
Vapor injection valve:
Chill, Frozen or Power Limit Mode:
When the cool capacity is 100 percent.
Compressor High Temperature
Protection:
When the compressor discharge
temperature exceeds 138 C (280 F).
3
Condenser fan pulses on and off on a 30
second duty cycle to maintain a minimum
condenser temperature:
Chill Loads:
Controller maintains a
minimum 30 C (86 F) condenser temperature.
Frozen Loads:
Controller maintains a
minimum 20 C (68 F) condenser temperature.
4
Digital Control valve modulates: Chill Loads
— whenever the unit is in a Cooling mode;
Power Limit — whenever the unit is in Power
Limit mode.
Operating Mode Function Chart
Chill Loads
Setpoints at -9.9 C
(14.4 F) and Above
Frozen Loads
Setpoints at -10 C
(14 F) and Below
Cool w/Mod
Heat
Defrost
Cool
Null
Defrost
Unit Function
•
1
•
Evaporator Fans High Speed
1
•
1
•
•
1
Evaporator Fans Low Speed
1
•
•
1
•
Evaporator Fans Off
1
•
•
Proportional-integral Derivative (Supply Air) Control
•
•
Return Air Sensor Control
•
•
Evaporator Coil Sensor Control
•
•
Compressor On
•
•
Compressor Vapor Injection On (valve energized)
2
•
•
Condenser Fan On
3
•
•
4
Digital Control Valve Modulating (energized)
4
•
5
•
•
•
Electric Heaters Pulsing or On (energized)
5
Summary of Contents for MP-4000
Page 2: ...Magnum TK 61110 4 OP Rev 0 11 13 En ...
Page 3: ......
Page 10: ...7 UNIT INSPECTION ...
Page 24: ...21 Controller Description ...
