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10.10 BRIEF POWER INTERRUPTIONS
Brief power interruptions (less than 0.5 second) may result in powered reverse rotation of single-phase
refrigeration scroll compressors. High-pressure discharge gas expands backward through the scrolls at
power interruption causing the scroll to orbit in the reverse direction. If power is reapplied while this
reversal is occurring, the compressor may continue to run noisily in the reverse direction for several
minutes until the compressor internal protector trips. This has no negative effect on durability. When
the protector resets, the compressor will start and run normally. Recommended is to use a timer which
can sense brief power interruptions and lock the compressor out of operation for two minutes. A three
minutes time delay is also suggested on three phase models to prevent frequent start/stop.
10.11 ELECTRICAL SUPPLY LINE AND CABINET SUPPLY CABLE
The electrical supply line of the finished product must be protected against over-
current, short-circuit, short-to ground. A Residual-Current Circuit Breaker (RCCB)
must be adopted. Design, components and installation must comply with the
applicable National and International Standards and regulations. The compressor
must be properly connected to ground.
Cables of the installation and of the compressor must be designed for appropriate
temperature, due to ampere load, and for voltage drop (see Table
10.1) taking into
consideration the max input current of the finished product and the compressor
LRA (Locked Rotor Amp), indicated for each model in the compressor label and
Embraco Product Selector on www.embraco.com and in Chapter 10.13
In any case, the supply cable, as well as all other installation cables, must be designed and protected in
order to comply with the applicable International standards and regulation, as well the National Standards
and regulations of the country where the system will operate.
For the compressor connection to the electrical supply line and for maintenance/
repairing operation, refer also to Appendix 1 - Recommendations - safety
instruction for compressor installation.
WARNING
WARNING
WARNING
10.12 MAXIMUM TEMPERATURE OF ELECTRIC MOTOR WINDINGS
The temperature of the motor windings should not exceed 130°C max. under normal running conditions.
The wiring temperature can be measured while the compressor is running through suitable equipment, or
through the method of ohmic resistance measurement, by disconnecting the compressor supply.
The compressor shall be connected to the supply line only when the hermetic
terminal cover is properly fixed. When the compressor is energized, all the electrical
measures must be done outside the cover.
CAUTION
