Siemens 3AH3 Operating Instructions Manual page 30

Description
Fig. 40 Undervoltage release (54.4)
30
Undervoltage release (Y7) 3AX1103
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 pos-
sible.
The undervoltage release Y7 has an electromagnet system that has voltage perma-
nently applied to it when the vacuum circuit-breaker is in the closed state. If the volt-
age 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. If this latter method is used, 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
A
B
Fig. 41 Typical circuit for connection of the undervolt-
age release Y7
R1 resistor
S1 auxiliary switch
Y7 undervoltage release
9229 9860 176 0E
2013-08-22