Siemens 3AH37, Operating Instructions Manual, Page: 30 / 64

Description
30 9229 9992 176 0D
2013-07-08
Undervoltage release (Y7) 3AX1103
The undervoltage release Y7 has an electromagnet system that has voltage
permanently applied to it when the vacuum circuit-breaker is in the closed state. If
the voltage drops below a certain value, the undervoltage release Y7 is unlatched,
thus initiating opening of the vacuum circuit-breaker via the stored energy
mechanism.
Random tripping of the undervoltage release Y7 is generally performed by an
NC contact in the tripping circuit, but can also be done with the aid of an NO contact
by short-circuiting the solenoid coil. In the case of this latter method, the solenoid
coil's short-circuit current is limited by the built-in resistor.
The undervoltage release Y7 can also be connected to voltage transformers.
The undervoltage release Y7 automatically trips the vacuum circuit-breaker if the
rated supply voltage drops to an inadmissible value. Any necessary varistors and
rectifiers are integrated in the release.
Power consumption ≤ 6.5 W or ≤ 7.5 VA
Note
The undervoltage release Y7 must only be operated with the supplied series
resistor R1.
Note
For switching operations (mechanical or electrical), the undervoltage release
3AX1103… must be connected to control voltage, as otherwise closing is not
possible (see “Removing the transport securing device from the undervoltage
release”, page 47).
Fig. 40 Undervoltage release (54.4) Fig. 41 Typical circuit for connection of the
undervoltage release Y7
A
B
R1 resistor
S1 auxiliary switch
Y7 undervoltage release