Home > Construction Training Manuals > Construction Electrician Intermediate > Table 7-2.Controller Troubleshooting Tips
WARNING
Indiscriminate jumping, however, should not be practiced because of the danger of short circuits. For example, a jumper should never be placed across a power-consuming device, such as a contactor coil; voltage or ohmmeters testers are used in this instance. If an ohm-meter is used to test a coil for continuity, the power must be OFF.
Table 7-2 is provided as an aid to servicing electric control equipment. Refer to the table to find the possible causes of a controller symptom.
Table 7-2. - Controller Troubleshooting Tips
| Controller Symptoms | Possible Causes and Recommended Items to Investigate |
| Arcing and burning of contacts | Should handle very little current and have sealing circuit; misapplied |
| Bellows distorted (on thermally operated devices) | Mechanical binding; temperature allowed to pass control limits |
| Blowout coil overheats | Overcurrent; wrong size of coil; loose connections on stud or tip; tip heating; excess frequency |
| Breakage, distortion and wear | Overheating; mechanical abuse; severe vibration; shock |
| Breakdown (of static accessories) | High temperature; moisture; overcurrent; overvoltage; corrosive atmosphere; mechanical damage; overload; ac on dc capacitor; continuous voltage on intermittent types |
| Broken flexible shunt | Large number of operations; improper installation; extreme corrosive conditions; burned from arcing |
| Broken pole shader | Heavy slamming caused by overvoltage; weak tip pressure; wrong coil; mechanical overload; low frequency |
| Bulbs distorted (on thermallv operated devices) | Liquid frozen in capillary tube |
| Burning and welding of control contacts and shunts | Shorts circuits on control circuits with too large protecting fuses; severe vibration; dirt; oxidation |
| Coil failure | Moisture; overvoltage; high ambient temperature; failure of magnet to seal in on pickup; too rapid duty cycle; metallic dust; corrosive atmosphere; chattering of magnet; wrong coil; holding resistor not cut in; intermittent coil energized continuously; mechanical failure; mechanical overload; mechanical underload; handling fluid above rated temperature |
| Contact opens prematurely | Dirt in air gap; shim too thick; too much spring and tip pressure; misalignment; not enough capacitance; not enough resistance |
| Contact takes longer than normal too open | Shim too thin; weak spring and tip pressure; gummy substance on magnet faces; too much capacitance; too much resistance |
| Contact-tip troubles | |
| a. Filing or dressing | Do not file silver tips; rough spots or discoloration will not. harm efficiency |