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12 Pressure Controls
Both high and low pressure controls are required and the following working pressures are recommended:
For ZFH models, the normal minimum setting should be 0.3 bar (R404A)
Maximum is 21 bar.
For ZSH and ZBH models operating without liquid injection, the LP cut out should be set as high as possible, normal
minimum 0.6 bar.
Both the high and low pressure controls are required and the following working pressures are recommended:
Low min:0.3bar, max. 21 bar. High :max 28 bar.
The high-pressure maximum is 28 bar.
13 Internal Pressure Relief Valve
There is an internal pressure relief valve for all horizontal scroll compressors, which opens at a differential pressure of
28 bar ±3 bar between high and low pressure sides.
14 Pump Down
To control refrigerant migration a pump down system could be used. The discharge check valve with refrigeration
scroll compressor is designed for low leak back and will allow the use of a pump down without the addition of an
external check valve.
If the compressor is stationary for prolonged periods, refrigerant could migrate into the compressor and therefore a
crankcase heater must be installed.
If constant cold air is drawn over the compressor, this could make the crankcase heater ineffective, and therefore a
pump down system is recommended.
For ZBH models, care should be taken because the scroll sets will unload at a pressure ratio of approximately 10:1. If
the unit fails to pump down, the pump down pressure should be reset to a higher value. The low pressure control
differential for all models needs to be reviewed since a relatively lower volume of gas will re-expand from the
discharge plenum of the compressor into the low side on shut down.
15 Shut-Off
The horizontal refrigeration scroll has a high volumetric efficiency valve in the discharge port, which stops the scroll
sets rotating in reverse, consequently no noise is apparent.
16 Starting
During the very brief start-up, a short metallic sound is audible, resulting from initial contacting of the spirals and is
normal.
No start assist devices are required for single-phase compressors, even if a system utilises non-bleed expansion
valves. Due to the design of the Copeland Scroll, the internal compression components always start unloaded even if
sys-tem pres-sures are not balanced. In addition, since internal compressor pressures are always balanced at start-
up, low-voltage starting characteristics are excellent for Copeland Scroll compressors. Moreover, if low voltage
conditions exist at start up, protector trips could result.
17 Deep Vacuum Operation
Do not run a Copeland scroll compressor in a deep vacuum. Failure to heed this advice can result permanent dam-
age to the compressor.
18 Electrical Installation
Independently from the internal motor protection, motor protection devices (fuses and circuit breakers) indicated by
F6...8 have to be installed before the compressor as shown in figure 4. Selection of the circuit breakers, fuses have to
be carried out according to VDE 0635 or DIN 57635 or IEC 269-1 or EN60-269-1.
Motor insulation material class is "B" according to VDE 0530 or DIN 57530 The Fusite connections are marked as in
figure 5.
C6.2.7/0302-0903/E
8
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