GE 239, Instruction Manual, Page: 21 / 158

GE Multilin 239 Motor Protection Relay 2-5
2 INSTALLATION 2 INSTALLATION
2
a) 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 con-
trol 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.
b) 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 1.4: SPECIFICATIONS at rated second-
ary 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
25*$1,=$7,21 &/$667<3( &7,1387 '(),1,7,216
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
IEC (Europe) 5P15 0.2VA 1 Amp P = Protection class
5 = Maximum %voltage error at limiting factor
15 = Limit factor, determines max. voltage CT can deliver to
load burden without exceeding the %voltage error
0.2 = Maximum amount of continuous burden allowed for
rated CT secondary
5P15 2.5VA 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.