Liebert 83 ユーザーズマニュアル

The Liebert Lee-Temp head pressure control system is designed to maintain proper operating head 

pressures in outdoor temperatures down to -30°F (-34.4°C). The condensers utilize head pressure con-

trol valves, extra refrigerant and insulated refrigerant receivers with heater pads. It works by flood-

ing the condenser coil with liquid refrigerant to a level that balances the system condensing 

requirements with the condenser coil surface available to reject the system heat. During the summer, 

the system requires the entire condenser coil surface for heat rejection and most of the refrigerant is 

stored in a receiver. In the winter, the same amount of heat can be rejected by only a fraction of the 

coil surface. As head pressure begins to fall, the control valve restricts the flow of liquid refrigerant 

exiting from the condenser. This extra liquid refrigerant reduces the effective condenser surface area 

available for heat transfer. The head pressure control valve also bypasses hot gas into the receiver to 

warm the liquid and maintain liquid pressure for proper operation of the expansion valve. Condenser 

fan controls are either fan cycling on ambient temperature or constant on. Lee-Temp control is 

required for Quiet-Line Condensers.

All Fan Speed and VFD Condensers are standard condensers with moderate operating sound levels. 

Lee-Temp Condensers with standard-size coils matching Fan Speed and VFD coil sizes are standard 

sound level condensers.

Quiet-Line condensers can help your facility meet the strictest noise codes and do so at less cost than 

traditional condensers with acoustical shielding. The Quiet-Line condensers utilize the same reliable 

construction features of the standard condensers and have oversized coils and slower speed fan 

motors which yield the required heat rejection needed at significantly lower sound levels. Lee-Temp 

control is required for Quiet-Line Condensers.

Transient Voltage Surge Suppression (TVSS) panel is standard in the VFD Condenser models only. 

Surge protection is necessary because rooftop voltage supply often is not conditioned the same as the 

voltage supply inside the data center. The TVSS is designed to protect sensitive electronic condenser 

components from high voltage transients, up to 25kVA/phase.
An illuminated green LED indicates power supply is On and panel status is OK. An illuminated red 

LED indicates conditions require service and the TVSS may require replacement to restore surge pro-

tection to the condenser.

Figure 2 shows a single refrigeration circuit diagram, displaying the indoor air conditioning unit, the 

outdoor condenser (VFD, Fan Speed Control or Lee-Temp) and field supplied interconnection piping.