11 Discharge
Temperature
Protection
Internal discharge temperatures reached under some extreme operating conditions (such as loss of charge or
extremely high compression ratio caused by failure of condenser fan) can cause compressor damage. In order to
guarantee positive compressor protection the compressor is equipped with a thermistor located in the discharge port
of the fixed scroll (Figure 6). Excessive discharge temperature above (120°C) will cause the electronic protector
module to trip. The discharge gas sensor is wired in series with the motor thermistor chain.
Figure 6: Discharge Temperature thermistor
12 Low
Ambient
Cut-Out
A low ambient cut-out may be required for systems using air as a heat source.
13 Pressure
Controls
A high pressure cut-out may be required according to individual national regulations and is strongly recommended
with three-phase compressors due to their capabilities of pumping to high pressures once the discharge is obstructed.
For the low-pressure side a minimum working pressure setting of 0.3 bar is recommended.
14 Shut off Sound
Scroll compressors may run backward for a brief period at shut off as the internal pressures equalise. A low mass,
disc-type check valve in the discharge tube of the compressor prevents high pressure gas entering the compressor
after shut down. Additionally there is a dynamic discharge valve mounted on the fixed Scroll, which effectively
eliminates reverse rotation.
15 Starting
During the very brief start-up, a short metallic sound is audible, resulting from initial contacting of the spirals and is
normal. Due to the design of the Copeland Scroll, the internal compression components always start unloaded even
if system pressures are not balanced. In addition, since internal compressor pressures are always balanced at
startup, low-voltage starting characteristics are excellent for Copeland Scroll compressors.
16 Deep-Vacuum
Operation
The danger of pulling deep vacuums is avoided due to an internal low vacuum protection which prevents the scrolls
pumping (unloads) when the pressure ratio exceeds approximately 20:1. In order to avoid nuisance trips, it is
recommended to set the low-pressure control as described in Section 13 above.
17 Electrical
Installation
Independently from the internal motor protection, fuses have to be installed before the compressor. Selection of fuses
has to be carried out according to VDE 0635 or DIN 57635 or IEC 269-1 or EN 60-269-1.
Motor insulation material class is “H” for models for all refrigeration scroll compressors, according to IEC 34-18-1, EN
0530, VDE 0530 or DIN 57530.
Recommended wiring diagram is shown in Figure 7.
C6.2.16/1004/E 6
