WoodMonger
Industrial
- Aug 22, 2007
- 2
We recently had an old analog soft start fail which we replaced with a new Baldor digital soft start. This is driving a 100hp fan motor for a dust collection system.
The original setup had no input contactor on the line-in side (just a nearby disconnect) and also had no bypass contactor to take the load of the soft starter once up and running.
This has worked fine for the last 12 years but it just doesn't seem to be the optimal setup. There is a safety issue in that there is 480v showing on the output side of the starter (in stopped state) unless the disconnect is switched off and then there is the issue of several hundred watts of heat being generated inside the enclosure by the SCR's on the soft start.
First order of business was to get the unit up and running again which we have done. Now I'd like to go back and correct the setup with a bypass contactor and possibly an input contactor. The problem is that a magnetic contactor sized for this motor costs nearly as much as the soft starter - and I need two of them!
My question then is do I need to install contactors rated for the FLA of the motor in question or can they be downsized due to the fact that they are not being used to switch the load?
Thanks in advance,
Conrad
The original setup had no input contactor on the line-in side (just a nearby disconnect) and also had no bypass contactor to take the load of the soft starter once up and running.
This has worked fine for the last 12 years but it just doesn't seem to be the optimal setup. There is a safety issue in that there is 480v showing on the output side of the starter (in stopped state) unless the disconnect is switched off and then there is the issue of several hundred watts of heat being generated inside the enclosure by the SCR's on the soft start.
First order of business was to get the unit up and running again which we have done. Now I'd like to go back and correct the setup with a bypass contactor and possibly an input contactor. The problem is that a magnetic contactor sized for this motor costs nearly as much as the soft starter - and I need two of them!
My question then is do I need to install contactors rated for the FLA of the motor in question or can they be downsized due to the fact that they are not being used to switch the load?
Thanks in advance,
Conrad