LG RCAW Operation & Maintenance Manual page 60

Service
n Voltage Monitoring Relay (5E)
The voltage monitoring relay is used for the verification of proper power supply of 400VAC. The voltage monitoring relay
is shown in the below. Existing 3-phase voltage will be shown ordinally every 3 seconds as shown in the below.
The voltage monitoring relay monitors 5 abnormal conditions of the power supply. The abnormal conditions include over
voltage, under voltage, phase reverse, phase loss, and voltage unbalance. Among the abnormal conditions, the phase
reverse and the voltage unbalance are selectively protective. The others are mandatory. When any abnormal condition
is encountered, the type of abnormal condition and abnormal value detected are displayed instead of normal display.
Some examples of the abnormal conditions are shown in the below.
Along with the selectivity of protection, reset method after any abnormal condition invocation can be configured through
4-position DIP switches. The functions of the DIP switches are shown in the below. According to factory setting, only the
switch positioned at ʻ5S/1Sʼ is off, and the others are on. Please don't change factory setting for proper protection.
60 Chiller Air-cooled Screw
R
S
T
R
S
T
R
S
T
Fig. 38
OVER VOLTAGE
R
V
S
T S
UNDER VOLTAGE
R
V
S
T S
PHASE LOSS
R
V
S
S
T
Fig. 39
V
S
V
S
V
S
REVERSE PHASE
R
V
S
T S
UNBALANCE VOLTAGE
R
V
S
T S
NO INPUT
R
V
S
S
T