TM 5-3895-374-24-1 Troubleshooting and Maintenance of Square D Motor Control Equipment WARNING: There is a hazard of electric shock or burn whenever working on or around electrical equipment. Turn off power supplying this equipment before working inside motor control centers Motor Control Trouble-Remedy Table -.-2    The  following  table  lists  troubles  encountered  with motor control, their causes and remedies This table is of a  general  nature  and  covers  only  the  main  causes  of trouble. Misapplication  of  a  device  can  be  a  cause  of  serious trouble,  however  rather  than  list  this  cause  repeatedly  it should   be   noted   here   that   misapplication   Is   a   major cause   of   motor   control   trouble   and   should   always   be questioned when a device is not functioning properly. Actual  physical  damage  or  broken  parts  can  usually  be found  quickly  and  replaced.  Damage  due   to   water   or flood conditions requires special treatment. Contact your local Square D office. TROUBLE CAUSE REMEDY Contact Chatter 1. Poor contact in control circuit. 1.    Replace the contact device or use holding circuit (Also see interlock (3 wire control). "Noisy Magnet") 2. Low voltage. 2.    Check coil terminal voltage and voltage dips. 1. Abnormal inrush of current. 1.    Check foregrounds, shorts, or excessive motor load current, or use larger contactor. 2. Rapid jogging. 2.    Install larger device rated for jogging service. 3. Insufficient tip pressure. 3.    Replace contacts and springs, check contact carrier for deformation or damage. 4. Low voltage preventing magnet from 4.    Check coil terminal voltage and voltage dips Welding or Freezing sealing. during starting. 5. Foreign matter preventing contacts from 5.    Clean contacts with Freon Contacts, starters, and closing. control accessories used with very small current or low voltage, should be cleaned with Freon. 6. Short circuit or ground fault. 6     Remove fault and check to be sure fuse or breaker size is correct. 1. Filing or dressing. 1.    Do not file silver tips Rough spots or discoloration will not harm tips or impair their efficiency. 2. Interrupting excessively high currents. 2.    Install larger device or check for grounds, shorts, or excessive motor currents. 3. Excessive jogging. 3.    Install larger device rated for jogging service. 4. Weak tip pressure. 4.    Replace contacts and springs, check contact carrier Short Tip Life or for deformation or damage entry of foreign matter into Overheating of Tips enclosure. 5. Dirt or foreign matter on contact surface.5 Clean contacts with Freon Take steps to reduce 6. Short circuits or ground fault. 6.    Remove fault and check to be sure fuse or breaker  size is correct. 7. Loose connection in power circuit. 7.    Clear and tighten. 8. Sustained overload. 8.    Check for excessive motor load current or install larger device COILS Open Circuit 1. Mechanical damage. 1.    Handle and store coils carefully. 1. Over voltage or high ambient tempera- 1.    Check coil terminal voltage which should not exceed ture. 110% of coil rating. 2. Incorrect coil. 2.    Install correct coil. 3. Shorted turns caused by mechanical 3.    Replace coil. damage or corrosion. 4. Under voltage, failure of magnet to seal. 4.    Check coil terminal voltage, which should be at Overheated Coil 5. Dirt or rust on pole faces. 5.    Clean pole faces. 6. Mechanical obstruction. 6.    WITH POWER OFF check for free movement of contact and armature assembly. (Page 3-147)