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What can be done to eliminate noise or chattering on a 8502 / 8536 SG NEMA size 5 device?

Basically, all AC devices which incorporate a magnet and armature assembly produce a characteristic hum. This hum is largely due to the changing magnetic pull (known as the flux change) which induces mechanical vibrations.

Contactors, starters and relays could become excessively noisy as a result of some of the following operating conditions: (1) broken shading coil, (2) inadequate control voltage, (3) incorrect coil, (4) misalignment between the Armature and the Magnet Assembly (Armature is unable to seat properly), (5) dirt, rust, filing etc., on the Magnet Pole Faces (Armature is unable to seat properly), (6) jamming or binding of moving parts (contacts, springs, guides, yoke bars) so that full travel of the armature is prevented, (7) incorrect mounting of the controller, such as on a thin piece of mounting plane fastened to a wall, for example a ``sounding board``.

AC magnet coils are designed to operate on line voltages fluctuating as much as 15% below and 10% above nominal rating. NEMA standards indicate the coil operating voltage can be as low as 85% and as high as 110% for suitable coil operation.

Vibration or ``Noise`` is very common in AC devices this large. Square D has designed a rectified coil circuit which eliminates the vibration issue. If the device is Size 5 Series A and 480-VAC or below, the best solution to address this issue is to replace the existing power plant assembly with the E-coil modification kit 9998SG***. Complete (***) the part number with the required coil voltage (ex: for 120-volt control voltage use 9998SG120, for 240-volt control use 9998SG240). If the device is Size 5 Series A and 600-VAC, order Series A replacement power plant assembly number 31096-613-50. NOTE: 31096-613-50 IS FOR USE WITH 600 VOLT SERIES A DEVICES ONLY! If the device is Size 5 Series B, verify the correct 31096-320-** rectified coil is being used. (An error in Digest 172 lists the replacement coils for Series B to be 31096-400 - this is an error - it should be 31096-320.)

This applies to all 8502SG, 8536SG, 8538SG, 8539SG, 8606SG, 8630SG, 8640SG, 8702SG, 8736SG, 8738SG, 8739SG, 8810SG, 8903SX, 8910SYD368, and 8940 Size 5, except ``NP`` devices. For enclosed devices, the series information is based on the device and not on the enclosure nameplate.

CTA-ID : 9675
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