Crompton Instruments 778 Data Sheet
CURRENT
TRANSFORMER
Model 778
Window Diameter 6.5"
Application:
Relaying and metering
Frequency:
50 - 400 Hz
Insulation Level:
600 Volts, 10 kv BIL full wave
Continuous Thermal Current
Rating Factor:
1.33 at 30ºC amb., 1.0 at 55ºC amb.
• Secondary terminals are No. 10 - 32 brass screws
with one flatwasher, lockwasher and regular nut.
• Approximate weight: 15 lbs.
E228202
0.13
Excitation Curve
1
100
9
8
7
6
5
4
3
2
1
10
1
100
9
8
7
6
5
4
3
2
1
10
1
100
9
8
7
6
5
4
z
H
3
0
6
E
2
G
A
T
L
O
1
10
V
9
Y
8
R
7
A
6
D
5
N
O
4
C
E
3
S
2
5000:5
4000:5
3500:5
3200:5
3000:5
2500:5
2000:5
1600:5
1500:5
1200:5
1000:5
800:5
600:5
500:5
400:5
300:5
250:5
200:5
150:5
100:5
75.5
50:5
CATALOG
NUMBER
778-500
778-750
778-101
778-151
778-201
778-251
778-301
778-401
778-501
778-601
778-801
778-102
778-122
778-152
778-162
778-202
778-252
778-302
778-322
778-352
778-402
778-502
CURRENT
RATIO
50:5
75:5
100:5
150:5
200:5
250:5
300:5
400:5
500:5
600:5
800:5
1000:5
1200:5
1500:5
1600:5
2000:5
2500:5
3000:5
3200:5
3500:5
4000:5
5000:5
ANSI METERING CLASS AT 60 Hz
RELAY
CLASS
B0.1 B0.2 B0.5
-
-
4.8
1.2
0.6
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
-
-
4.8
1.2
0.6
0.6
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
-
-
-
C10
C10
C10
C20
C20
C20
C20
C50
C50
C100
C100
C50
C50
C100
C100
C100
C20
C20
4.8
2.4
1.2
1.2
0.6
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
1.50
SECONDARY
WINDING
B1.8
-
-
-
-
-
-
4.8
2.4
1.2
1.2
0.6
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
RESISTANCE
(OHMS @ 75 C.)
0.010
0.016
0.021
0.032
0.043
0.053
0.064
0.086
0.107
0.128
0.171
0.214
0.263
0.328
0.350
0.473
0.592
0.710
0.757
0.828
0.719
0.898
B0.9
-
-
-
-
-
-
-
4.8
2.4
2.4
1.2
0.6
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
1
1
1 2 3 64 5 7 8 9 1 2 3 64 5 7 8 9 1 2 3 64 5 7 8 9 1
.01 .02 .05 0.1 0.2 0.5 1.0 2.0 5.0 10.0
SECONDARY EXCITING CURRENT 60Hz
Section 4
11
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