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CHAPTER 2: INSTALLATION
Voltage inputs
NOTE:
NOTE
NOTE:
NOTE
Control power
CAUTION:
CAUTION
CAUTION:
CAUTION
CAUTION:
CAUTION
NOTE:
NOTE
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
The relay has three channels for AC voltage inputs, each with an isolating transformer.
Voltage transformers up to a maximum 300:1 ratio may be used. The nominal secondary
voltage must be in the 50 to 240 V range. The three phase inputs are designated as the
"bus voltage". The Bus VT connections most commonly used, wye and delta (or open delta),
are shown in the typical wiring diagram.
If Delta VTs are used, the zero sequence voltage (V
connection, the phase-neutral voltage cannot be measured and will not be displayed.
The relay can be applied to both metering and protection feeders with up to 20000 V
phase-to-phase voltage. Please ensure that the selected VT ratio and VT secondary do not
result in a primary voltage exceeding 20000 V.
Control power supplied to the relay must match the installed power supply range. If the
applied voltage does not match, damage to the unit may occur. All grounds MUST be
connected for safe, normal operation regardless of control power supply type.
The label found on the relay specifies its order code or model number. The installed power
supply's operating range will be one of the following:
LO: 24 to 48 V DC (Nominal Range: 20 to 60 V DC)
HI: 125 to 250 V DC/120 to 240 V AC (Nominal Range: 84 to 250 V DC/60 to 300 V AC)
The relay chassis ground terminals should be connected directly to the ground bus,
using the shortest practical path. A tinned copper, braided, shielding and bonding
cable should be used. As a minimum, 96 strands of number 34 AWG should be used.
Belden catalog number 8660 is suitable.
Isolate power prior to servicing.
An external switch, circuit breaker, or other protective device must be connected close to
the equipment.
ELECTRICAL INSTALLATION
) will be zero. Also, with the Delta VT
0
2–15
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