Under-Over Voltage Transformer
RTHC-SVD01B-EN 35
Section 5 Under-Over Voltage Transformer
5-1. General
The hardware required for the Under-Over Voltage sensing function of
UCP2 is optional on RTHC units. This option must be installed in the
Machine Configuration Menu (+-+-+-) and for Under-Over Voltage pro-
tection to be active, Under-Over Voltage protection must be enabled in
the Field Start-up Menu (++--++). Three custom designed transformers
whose primary is connected across the Line Voltage phases, provides
a stepped down and isolated AC voltage to the Starter module at input
J3. This secondary voltage is directly proportional to the line voltage
applied to the primary.
The Compressor Report on the CLD can display the Compressor
Phase to Phase Voltages and, when so enabled, can cause an MAR
(machine shutdown-automatically resettable) diagnostic for High and
Low Line voltage conditions. With the Under-Over Voltage Protection
enabled, an Over Voltage diagnostic will start integrating to trip if the
line voltage is above 10% of the nominal voltage set in the Machine
Configuration Group under Service Settings menu. The Under Voltage
diagnostic will start integrating to trip if the line voltage drops below
10% of the nominal voltage. Trip time is a minimum of 1 minute to a
maximum of 5 minutes.
WARNING
Live Electrical Components!
During installation, testing, servicing and troubleshooting of this prod-
uct, it may be necessary to work with live electrical components. Have a
qualified licensed electrician or other individual who has been properly
trained in handling live electrical components perform these tasks. Fail-
ure to follow all electrical safety precautions when exposed to live elec-
trical components could result in death or serious injury.
5-2. Under-Over Voltage Transformer Checkout
Locate the Under-Over Voltage Transformers [2T6, 2T7, 2T8] in the
panel by referring to the Component Location Drawing. Carefully mea-
sure the primary voltage across each transformer and note the value in
VAC rms.
Next, disconnect the transformer’s secondary from J3 on the Starter
module. Using voltmeter probes, measure and note the unloaded sec-
ondary voltage (VAC rms) (low voltage class 2 less than 32 VAC).
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