Wednesday, February 18, 2009

b)Unstable control voltage


Unstable control voltage


Unstable control voltage can be the result of

- an insufficiently sized control transformer




- drop of the line voltage during motor starting




- relay contacts in the control circuit of the contactor which are not sufficiently rated to handle the closing power consumption of the contactor magnet coil. This leads to relay contact bouncing and subsequent welding of contactor main contacts

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