3Va27 / 3Wl10 For Motor Protection Applications - Siemens SENTRON 3WL10 Manual

Description
2.6 Possible uses and portfolio
2.6.4

3VA27 / 3WL10 for motor protection applications

Both the current-carrying 3WL10 and the current-limiting 3VA27 are suitable and can be
used for motor protection.
First of all, the usability of both device classes is verified by checking the maximum short-
circuit power of the transformer / generator.
The following must be considered: In the 3VA27, the molded case circuit breaker reduces
the let-through currents above approx. 32 kA in case of a short-circuit, i.e. the load reaching
downstream equipment, e.g. contactor and motor, is lowered (less thermal load, lower
dynamic forces).
However, the 3VA27 also trips instantaneously above the max. I
The 3WL10, however, is designed to prevent automatic lifting of the contacts above the max.
I to avoid unwanted tripping of the device.
i
That makes it more robust against high inrush currents and false tripping on motor starting.
The starting function suspends the parameters set within the limits of the electronic trip unit
(<I max = 15xI
i
heavy starting) without unwanted tripping.
After the set active starting time during starting, the parameters are automatically set to the
set values again.
The setting options on the electronic trip units (ETUs) are identical on 3VA27 molded case
circuit breakers and 3WL10 air circuit breakers.
26
) equally on both devices to withstand certain starting characteristics (inrush /
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3VA27 molded case circuit breakers & 3WL10 air circuit breakers
Manual, 10/2018, L1V30499596002-01
(15xI ).
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