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Inner View of Stabilizer : -
Introduction :
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| Voltage fluctuation is a common phenomenon in every part of the country. The industrial units running round the clock, usually face the problem of low and high voltage. 90% of industrial load is of motors. Electric motors draw considerably high current at low & high voltage. This higher current affects the electrical motors (particularly smaller capacity motors upto 7.5 H.P.) in three ways. |
| 1. |
Higher current produces higher losses in electrical motors which causes premature failure of winding. |
| 2. |
These higher losses of electric motors also increase the losses of cables, switches, transformers and other associated equipments. |
| 3. |
For smooth continuous operation of motors, overload relays are usually set at 20% higher setting. |
ADVERSE EFFECTS OF SINGLE PHASING : -
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| (a) |
The line current increases by 1.5 times. |
| (b) |
If the relay setting is at 15-20% higher than actual operating current then the relay will take 4-6 minutes to trip. |
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(c)
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The motor (particularly smaller capacity motors upto 7.5 H.P.) cannot withstand this high current for such a long time and in most of the cases it burns out before the relay trips. |
| (d) |
Heavy short circuit current flows through the relays, contactors, cables etc. |
| (e) |
Under this condition when the relay, contactor trips, they produce sparks and some times bursts.. |
| (f) |
This further damages the switchgear and in some of the cases may cause fire also. |
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With the installation of the stabilizer and maintaining 390/400 volts, the motor will operate smoothly drawing 15-20% lesser current and correspondingly the relay setting can be reduced by 15-20%. In case single phasing occurs, the relay will trip in 40-50 seconds. The motor can withstand the high current for this period and will be safe. Also, the relays, contactors, switch gears, etc. Incorporated with the motor will be safe.
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