GE Digital Energy Multilin 239, Инструкция по эксплуатации

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CHAPTER 2: INSTALLATION
239 MOTOR PROTECTION RELAY – INSTRUCTION MANUAL 2–21
CONTROL POWER (36/37)
A universal AC/DC power supply is standard. It covers the range 90 to 300 V DC and 70 to
265 V AC at 50/60 Hz. It is not necessary to make any adjustment to the relay as long as
the control voltage falls within this range. A low voltage power supply is available upon a
request of MOD# 501. It covers the range 20 to 60 V DC and 20 to 48 V AC at 50/60 Hz.
Verify from the product identification label on the back of the relay that the control voltage
matches the intended application. Connect the control voltage input to a stable source of
supply for reliable operation. A 2.5 A fuse is accessible from the back of the unit without
opening the relay by sliding back the fuse access door.
PHASE CT INPUTS (1-9)
Current transformer secondaries of 5 or 1 A can be used for current sensing. Each phase
current input has 3 terminals: 5 A input, 1 A input, and common. Select the 1 or 5 A
terminal and common to match the phase CT secondary. Observe the polarity indicated in
the TYPICAL WIRING DIAGRAM, otherwise current measures incorrectly for the 2-phase or
residually connected CT configurations.
CTs should be selected to be capable of supplying the required current to the total
secondary load which includes the 239 relay burden mentioned in Section 1.2:
Specifications at rated secondary current and the connection wiring burden. The CT must
not saturate under maximum current conditions which can be up to 8 times motor full load
during starting or greater than 12 times during a short circuit. Only CTs rated for protective
relaying should be used since metering CTs are usually not rated to provide enough
current during faults. Examples of typical CT ratings are:
Table 2–3: Typical CT Ratings
ORGANIZATI
ON
CLASS TYPE
239 CT
INPUT
DEFINITIONS
CSA (Canada)
10L4 B0.2 1 Amp
L = Protection class
10 =10% ratio error
4 = Voltage the CT can deliver to load burden at 20
×
rated
secondary current without exceeding the 10% ratio error
B0.2 = Maximum burden (0.2
Ω
) that can be put on the
transformer without exceeding the 10% ratio error
10L20 B0.2 5 Amp same as 1 Amp input
ANSI (USA)
10T4 B0.2 or
10C4 B0.2
1 Amp
T = Ratings determined by Tests
C = Ratings determined by Calculations
10 = 10% ratio error
4 = Voltage the CT can deliver to load burden at 20
×
rated
secondary current without exceeding the 10% ratio error
B0.2 = Maximum burden (0.2
Ω
) that can be put on the
transformer without exceeding the 10% ratio error
10T20 B0.2 or
10C20 B0.2
5 Amp same as 1 Amp input
NOTE: The sizes shown above may not be standard CT ratings. The numbers are merely used to indicate what size
CTs can be used with the 239.