Siemens SENTRON 3WA1 - Connection of an External Voltage Transformer; Description

Accessories
4.13 Connection of an external voltage transformer
3WA1 air circuit breaker
368 Equipment Manual, 02/2023, 92310000002-06
4.13 Connection of an external voltage transformer
4.13.1 Description
A circuit breaker with the ETU600 electronic trip unit can be configured with an optional
metering function. An internal voltage tap or an external voltage transformer in
conjunction with a VTM voltage tap module is required for measuring the voltage.
It is possible to retrofit the connection for an external voltage transformer on size 2 and
size 3 circuit breakers with ETU600.
The retrofit kit comprises:
• Internal cable harness
• Voltage tap module VTM640
• Components required for the secondary disconnect terminal
The voltage transformers are connected in a star connection to terminals X9-1 to X9-4 of
the secondary disconnect terminal of the circuit breaker.
Please comply with the following specifications for connecting external voltage
transformers:
• Primary voltage U
pr
= 100 V AC to 690 V AC (selection according to phase voltage of
the system)
• Secondary voltage U
sr
= 100 V AC to 120 V AC
• Output load of the voltage transformers through the ETU600 electronic trip unit: 100 kΩ
• The 1% measuring accuracy for the voltage requires voltage transformers in accuracy
class 0.5.
The transformation ratio of the voltage transformers must be set on the ETU600
electronic trip unit. This can be done in menu item 5.3.4 "Voltage measurement" using
the operating keys on the display of the ETU600 electronic trip unit or with the help of
the SENTRON powerconfig commissioning and service software.