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Hersteller: Liebert Dateigröße: 2.77 mb Dateiname: Unterrichtssprache:

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Table 6 60Hz condenser data, Quiet-Line (Lee-Temp controlled/fan-cycling) . . . . . . . . . . . . . . . . . . . . . . 19 Table 7 50Hz condenser full load amp values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Table 8 Lee-Temp receiver electrical data, 50Hz and 60Hz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Table 9 Troubleshooting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 ii Introduction 1.0 INTRODUCTION 1.1 Product Description and Features The Liebert condenser is low-profile direct-drive propeller fan-type air cooled unit suitable for mounting outdoors. It provides for the heat rejection of either one or two separate refrigeration circuits, matching heat rejection capacity varying with the outdoor ambient temperatures with each corresponding compressors heat rejection requirements. Constructed with an aluminum cabinet and a copper- tube aluminum fin coil, the unit is quiet and corrosion resistant. The condenser is quickly and easily installed, because all internal wiring is completed at the factory with only electrical connections to be made at the job site. All electrical connections and controls are enclosed in an integral weatherproof section of the condenser. Figure 1 Liebert two-fan condenser 1.2 Head Pressure Control Types 1.2.1 Fan Speed Fan speed control utilizes a wave-chopper control to vary the air volume over the condenser coil, based on refrigerant head pressure. The fan motor next to the electrical panel (two fans on 6-fan and 8-fan models) is a single-phase, permanent split capacitor motor with motor speed adjusted in response to refrigerant pressure. The balance of fans on multi-fan units cycle on ambient thermostats. The control system provides refrigerant head pressure control for outdoor ambients as low as -20°F (-28.9 °C). 1.2.2 Variable Frequency Drive VFD Condenser control system utilizes a variable frequency drive, inverter duty fan motor operating from 0% to 100% motor RPM based on head pressure, sensed by refrigerant pressure transducers. VFD, ambient-temperature thermostat(s), motor overload protection and electrical control circuit are factory-wired in the integral control panel. VFD controls the fan adjacent to the connection end of the condenser and remains energized with active compressor operation. The balance of fans on multi-fan units cycle on ambient thermostats. This system provides refrigerant head pressure control for outdoor ambients as low as -20°F (-28.9°C). 1 Introduction 1.2.3 Liebert Lee-Temp™ Refrigerant Control 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 control valves, extra refrigerant and insulated refrigerant receivers with heater pads. It works by flooding 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. 1.3 Sound Level Options 1.3.1 Standard Condenser 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. 1.3.2 Quiet-Line Condenser 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. 1.4 Transient Voltage Surge Suppression Option 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 t...

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