Compressor Crankcase Heaters; Rrucm And Reliatel Controls - Trane RRU120 D B Series Installation, Operation And Maintenance Manual


Observe the ABC and CBA phase indicator lights on
the face of the sequencer. The ABC indicator light will
glow if the phase is ABC. If the CBA indicator light
glows, open the disconnect switch or circuit
protection switch and reverse any two power wires.

Restore the main electrical power and recheck the
phasing. If the phasing is correct, open the disconnect
switch or circuit protection switch and remove the
phase sequence indicator.

Compressor Crankcase Heaters

Each compressor can be equipped with a crankcase
heater. The proper operation of the crankcase heater is
important to maintain an elevated compressor oil
temperature during the "Off" cycle to reduce oil foaming
during compressor starts. Oil foaming occurs when
refrigerant condenses in the compressor and mixes with
the oil. In lower ambient conditions, refrigerant migration
to the compressor could increase.
When the compressor starts, the sudden reduction in
crankcase pressure causes the liquid refrigerant to boil
rapidly causing the oil to foam. This condition could
damage compressor bearings due to reduced lubrication
and could cause compressor mechanical failures.
Before starting the unit in the "Cooling or
Dehumidification" mode, remove the jumper on terminals
5 and 6 (Energy Stop) and turn the main power disconnect
to the "On" position and allow the crankcase heaters to
operate a minimum of 8 hours.
Before closing the main power disconnect switch, insure
that the "Control Input" input is in the "Unoccupied" or
connection on RRUTS 7 an 8 is "Open."
Close the main power disconnect switch and the unit
mounted disconnect switch, if applicable.

RRUCM and ReliaTel Controls

Upon power initialization, the controls perform self-
diagnostic checks to insure that all internal controls are
functional. The Status LED located on the RRUCM and the
Liteport LED located on the RTRM module is turned "On"
within one second of power-up if internal operation is
okay.
RRU-SVX01F-EN
Installation
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