Saturday, May 10, 2014

Direction change in VFD'S

In starters such as Star- Delta Starters, DOL Starters, Soft Starters whenever there is need of changing the direction of motor than that will be done by changing I/P leads, output leads of supply. This will leads to lot of effort making. This will also leads to loose connections. 
There are also phase change-over's available in market for changing direction of motor. 
In VFD connected motors if motors direction is need not be changed then there is no need to changing input and output connections. Below will explain the same:-

Most often question comes in mind that is how to change direction of motor in VFD’s??

In VFD’S we can’t change the direction of motor by changing phase sequence from I/P supply. As in VFD’S motor I/P get converted into DC supply thereafter AC O/P will be generated through inverter. As any phase sequence of AC supply will get converted into DC thereafter that will converted into AC supply so Phase sequence will always remains same even after changing phase sequence.

In VFD’S direction can be changed by changing option available in VFD’S which will change the direction i.e. direction can be changed by simply changing programming in control circuit. Option may b available in VFD’S depending upon VFD manufacturer it may either ABC and ACB or RYB or YRB.

During initial startup of motor and reversing the motor there is often need of changing the direction of motor than same will be done as per method stated above.

But this doesn't imply that you can install VFD's for keeping the direction same for VFD's, as VFD's are very costly than other starters.