The Crankcase Heaters
The majority of compressors have crankcase heaters. This is because most Air conditioning and commercial system started from a big part of the refrigerant charge in the system compressor. It especially when the device is idle for some time, or when the compressor is started for the first time. The start-up refrigerant boils off, taking oil charge. This means that the compressor is forced to work long as 3 or 4 minutes, until the charge of oil circulating system, and returns to the crankcase. Obviously, this reduces the service life of the compressor.
The decision to charge the system so that little or no refrigerant collects in the crankcase and control crankcase heater for at least 12 hours before the beginning or after long periods of inactivity.
Two types of the crankcase heaters General compressors. The wrap-around type is usually called a belly band.
Another type is the start of the vessel off-cycle thermal method.
The smell of the heater should be tied to the housing below the oil level and in close contact with the case. Good heater will maintain the oil at least 10F (5C) above the temperature of any other system components. When the compressor is stopped, it will support at or above the minimum temperature of 80 F (27C).
The launch of the tank, out-of-cycle thermal method, single phase compressor stops open only one leg (L1). Thus, the other leg to the power supply (L2) capacitor, remains hot. Trickle current through the starting winding results, thereby warming the motor windings. Thus, the oil is heated on off-cycle
Make sure that you pull the switch that disables the entire block with power supply before starting to work with this system. Sump capacity heating systems, can be detected one or more of the following:
Contactor or thermostat breaks only one leg of the compressor and condenser fan.
Equipment provides notification that the authorities, at the compressor, when he is not working and that the switch must be open before servicing.
Capacitor, sometimes split (it consists of three terminals), so that only a part of the capacity is used for off-cycle heating.
Basic connection diagram for JSC compressor run the vessel off-cycle heat shown in Fig. 9-53.