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How to prevent Chattering Contactor ?

The primary cause of abnormal connection exhaustion is chattering, which is caused by

the symptoms described below. It is necessary to increase prevention.

•Discordance between rated coil voltage, frequency, and source voltage

- In the case of discordance between rated coil voltage, frequency, and source voltage (ex. In the case of connecting 220V coil to 110V source)

- Coil may be changed to fit the source voltage.

•Low voltage, rapid voltage drop

- In the case that commitment of the contactor makes the startup current of a motor flow to make the voltage drop larger (over 35%), the contactor repeats close, voltage drop, open, voltage recovery, reclose, and voltage drop, and a frequency of chattering occurs at a frequency of once every 20~50msec.

- Due to the causes are described below, maintenance will be required, and since a rapid voltage drop can hardly be measured by a tester, taking a measurement with an oscilloscope is needed.

•Leakage of source capacity

•Too small sized wire

•Too far from source

•Inappropriate startup (simultaneous startup of many motors)

•Operating connection chattering

- The connection which controls the coil of an contactor causes chattering by electrical or physical cause from foreign parts.

- When the connection of control circuit is vibrated by electrical or physical shock from s foreign source, the exciter of the operating coil of an contactor can be shorted and cause the chattering.

- The causes are described below, it is necessary to investigate and improve them

•The connection of relay is vibrated by the shock of a contactor commitment due to install the relay close to the contactor (bouncing)

•The connection of pressure switch, float switch, or limit switch is vibrated (bouncing). Or, it acts an unstable way.

•The structure of the pressure or preparation the sticking causes vibration.

•Insufficient connection for the terminal (badness of screwing and soldering)

•Because coil voltage is too high, closing impact is big.

•Loose coil terminal

- In case of voltage drop caused by loose of the connecting line of coil terminal screw

- Connect coil terminal with the appropriate torque as the written in the catalog.

•Incorrect installation of main body

- The connection is bouncing as the structure of control board or inappropriate installing of the main body of contactor.

- Install the right method of installation as is written in the catalog.

check the structure of control board without vibration of contactor by switching.

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