Effect of Unbalanced Input Voltage between Phase to Phase
Industrial units located in residential and commercial areas, which do not have their own distribution transformer, have the problem of unbalance input voltage between phase to phase. They many also have the problem of frequent failure of three phase motors.
Normally unbalanced input voltage problem persist for few hours in a day and will have the following effects on the three phase motors
- With 5% Unbalanced Input Voltage between phase to phase, the LOAD will be unbalanced and the capacity of the motor reduces by 40%.
- Consumption of the three phase motor will increase by 20 to 25%.
Setting of motor relay is kept higher than actual required in order to avoid frequent tripping of the overload relays and to continue production. The motors which are particularly smaller motors up to 7.5 H.P. cannot withstand this high current for long duration. In many cases the motor burns out and this high current flows through the relays, contactors, cables etc. which result in failure of the same and in some of the cases may cause fire also.
The best solution for such units having unbalanced input voltage, is to install Servo Voltage Stabilizer with Individual phase Control. |