Siemens Sentron 3VA Manual page 21

Electronic trip unit (ETU)
The current sensor of the 3VA6 molded case circuit breaker comprises an iron-cored
transformer for the internal power supply and a Rogowski coil for precise sensing and
measurement of the current values. Each of these transformers was specifically optimized
for its task. Thanks to the high accuracy of current measurement achieved by the Rogowski
coil, the 3VA6 molded case circuit breaker is suitable for power and energy measurement. In
addition, finer adjustment of ground fault current monitoring is possible.
The electronic trip units (ETUs) provide the following protection functions:
● Overload protection L ("L" = Long-time delay)
Adjustable in steps from 40% to 100% of the rated operational current of the molded case
circuit breaker.
● Short-time delayed short-circuit protection S ("S" = Short-time delay) for time-selective
response in case of a short circuit
● Instantaneous short-circuit protection I ("I" = instantaneous):
● Protection of the neutral conductor against overload and short-circuit ("N" = neutral)
● Protection against residual currents to ground ("G" = Ground fault).
Two possibilities are available for protection against residual currents to ground:
● Tripping of the breaker when a ground fault is present and thus disconnection of the
system
● Alarm-only indication, via LED, that a ground fault is present. The signal is also available
through communication and a digital output, when applied with the appropriate
accessories.
The breaker is not tripped here, the system remains connected although the ground fault
still exists.
3VA6 molded case circuit breakers with corresponding ETUs are available for both
applications.
Energy management and communication
The Electronic Trip Units (ETUs) provide the following energy management and
communication functions:
● Metering functions for current, voltage, power and energy consumption
● Transfer of measured values and status information of the circuit breaker
● Remote parameter assignment of tripping thresholds and miscellaneous parameters
● Flexible use of digital inputs and outputs of the optionally available EFB300 external
function box
● Commissioning/setting the plant topology and also individual breaker parameters with the
"powerconfig" software package
● Testing and archiving with the TD300 and TD500 test devices (with powerconfig)
3VA molded case circuit breakers with UL and IEC certification
Manual, 01/2019, L1V30435333-01
2.1 Overview - applications and portfolio
Description
19