nader NDW3 Series Manual page 48

4.4 Related Accessories of Controller
4.4.1 External N-pole transformer
 Ground type
The 3P+N system can be formed by using a 3P circuit breaker and an external N-phase transformer.
It can measure data on the grounding cable via an external N-pole transformer to realize the ground
protection of the differential type (T) or the ground current type (W). The electric circuit diagram is
shown as below:
1) Electric circuit diagram of differential type (T)
Intelligent
controller
3P
2) Electric circuit diagram of ground current type (W)
◆ Transformer type
For rectangular and flexible-type transformers, users can select the frame size current (or N-pole
current) and dimensions.
1） Rectangular transformer
★ Rectangular transformer code
Transformer code
N1
N2
N3
N4
Internal & confidential file
File No.:NDT2920202
Intelligent
controller
4P
Intelligent
controller
3P+N (W)
Hole dimensions mm
62×21
102×32.5
122×52
262×102
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PE or PEN
Applicable frame size
1600
1600, 2500
2500, 4000, 6300
4000, 6300, 7500
File Version:4
Intelligent
controller
External N-phase
transformer
3P+N (T)