Current and Voltage Controls
Current Transformer, 3-Phase
Types A 74-10, A 74-11
• 3-phase current metering transformers
for use with current control relays
• Measuring ranges:
A 74-10 5:
0.5 -
5 AAC
A 74-10 20: 2 - 20 AAC
A 74-11 100: 10 - 100 AAC
A 74-11 500: 50 - 500 AAC
Product Description
3-phase current transformer
measures on all three phases.
Output voltage proportional
to measured amplitude of the
rms-value of the normal
phase current.
Ordering Key
Type
Input current
A 74-10 5
Type Selection
Input current
5 AAC
20 AAC
100 AAC
500 AAC
Type no.
A 74-10 5
A 74-10 20
A 74-11 100
A 74-11 500
Input Specifications
A 74-10 5
Current range
Max. current
(continuously)
Max. overload current
(t = 30 s)
Rated insulation voltage
Input-output
Overvoltage category
Dielectric strength
Dielectric voltage
Rated impulse withstand volt.
Power consumption
0.5 - 5 AAC
20 AAC
40 AAC
1000 VAC
rms
IV (IEC 60664)
6 kVAC
rms
12 kV (1.2/50 µs)
< 0.1 W@5 A
A 74-10 20
2 - 20 AAC
50 AAC
85 AAC
1000 VAC
rms
IV (IEC 60664)
6 kVAC
rms
12 kV (1.2/50 µs)
< 0.25 W@20 A
A 74-11 100
10 - 100 AAC
250 AAC
325 AAC
1000 VAC
rms
IV (IEC 60664)
6 kVAC
rms
12 kV (1.2/50 µs)
< 1.5 W@100 A
A 74-11 500
50 - 500 AAC
750 AAC
1000 AAC
1000 VAC
rms
IV (IEC 60664)
6 kVAC
rms
12 kV (1.2/50 µs)
< 21 W@1500 A
Output Specifications
A 74-10 5
Output voltage
(T
A
= 20°C = 68°F), R
L
= 9.5 kΩ)
Output impedance
Tolerance of output voltage
@ rated input current
Temperature variation
Rated insulation voltage
(cable)
A 74-10 20
A 74-11 100
A 74-11 500
0.4 - 4 V
p
< 700
Ω
± 5%
± 0.1% per °C
250 VAC
rms
0.4 - 4 V
p
< 200
Ω
± 5%
± 0.1% per °C
250 VAC
rms
0.4 - 4 V
p
< 40
Ω
± 5%
± 0.1% per °C
250 VAC
rms
0.4 - 4 V
p
< 10
Ω
± 5%
± 0.1% per °C
250 VAC
rms
Specifications are subject to change without notice (19.07.06)
1
A 74-10, A 74-11
General Specifications
Pollution degree
Ambient temperature
Housing
A74-10
Dimensions
A74-11
Material
Weight
A 74-10
A 74-11
Connection cable
Approval
CE Marking
3 (IEC 60664)
- 20 to + 60°C (- 4 to + 140°F)
120 x 45 x 16 mm
150 x 114 x 23
ABS
200 g
750 g
2 m PVC, 4 x 0.4 mm
2
UL
Yes
Mode of Operation
The current metering trans-
former is connected to the
current control relays H 475
as follows:
Red
core to
term. 5
White
core to
term. 6
Yellow
core to
term. 7
Black
core to
term. 8.
(starpoint - neutral).
- U
1
.
- U
2
.
- U
3
.
ductor through the hole sever-
al times makes it possible to
meter currents below the no-
minal range.
If the conductor is drawn
through the central hole e.g. 5
times, the metering trans-
former will register 50 A when
the current in the conductor is
10 A.
In amplitude and phase the
output voltage is proportional
to the phase current metered.
The metered conductor is
drawn through the central
hole of the current metering
transformer. Drawing the con-
Wiring Diagrams
Input current
Correct connection
Output voltage
U
1
Red
Black
U
3
Yellow
Incorrect connection
U
1
Red
U
2
White
Black
U
3
Yellow
U
2
White
Red
White
Yellow
Black
Dimensions
A 74-10 ..
A 74-11 ..
2
Specifications are subject to change without notice (19.07.06)
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