Causes and Dangers of Single Phasing in AC Motors
In AC Motors, the loss of current through one phase of a three-phase supply is a process described as single phasing. During single phasing , there are no currents passes through one line, whilst, depending on the load, excessive current flows through the other two lines.
There are many causes of single phasing to be mindful of with your AC Motors:
- Blown Line Fuse or broken line wire.
- Terminal contacts of AC Motors may be broken due to vibration or ageing.
- In contactor relays, one contactor may not be making proper contact. Or the contact spring could be damaged, or weak.
- Contact joints may possibly be covered with oxidation product.
Effects of single phasing in AC Motors can include…
- Uneven current distribution in the motor can cause damage.
- Motor will vibrate considerably causing a humming noise. Although it carry on running, once it is stopped the AC Motor will not re-start.
- Fluctuation in RPM.
- Generator overloading.
- Leading to an electrical fire.
- Melting of insulation, which can directly lead to electric-shock-causing short circuiting or earthing.