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12 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 must be equipped with an external discharge temperature
sensor. This thermostat is not insulated and the equivalent set point for an insulated sensor is 120°C maximum. A
thermostat should be positioned as shown in Figure 12 below.
Figure. 12. Discharge line thermostat
13 Standard Motor Protection
Conventional inherent internal line break motor protection is provided with models ZH13KVE and ZH18KVE.
14 Low Ambient Cut-Out
A low ambient cut-out may be required for systems using air as a heat source.
15 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.
16 Shut-Off
A check valve in the discharge connection of the compressor prevents the compressor from running backwards for
more than a second or two. This momentary reversal of direction of the scrolls has no effect on compressor durability
and is entirely normal. Additionally there is a dynamic discharge valve mounted on the fixed Scroll, which effectively
eliminates reverse rotation.
17 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.
18 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 15 above.
C6.2.17/1004/E
11
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