Do I need over current protection?

mjbarcelona · Sep 2, 2019

Hi guys, sorry I haven't really send all the details about this, I've attached a photo of the diagram that the manual says, It says to put thermal overload relay? plus fuse upstream the soft starter? I'll be using this for a pump, I've also attached the photo of the details of the pump. Thanks much for helping and responding!

[ElectriciansForums.net] Do I need over current protection?

Bobster · Sep 2, 2019

davesparks said:
There is a common misconception in the UK that overloads need setting at more than the FLC, but normally they should be set at FLC as they are designed so that they cope with the inrush fir that setting.

It's a hangover from the old oil filled dashpots that were used for OL protection. These you had to have set at 100% FLC.

In regard to the OP, if the manufacturers state you need OL protection, then you need it. Maybe this model of SS doesn't have built in OL protection.

bomjac · Sep 3, 2019

Fuse it (or use MCB) upstream of the starter to protect the equipment from short circuit, and use the overload to protect the motor from overload. You can use a combination MCCB for the complete protection provided it is of the correct type and is adjustable to the nominal motor current.

In the UK our regulations state that all motors above 0.37kW must have overload protection, I imagine your regulations will be similar.

netblindpaul · Sep 3, 2019

bomjac said:
Fuse it (or use MCB) upstream of the starter to protect the equipment from short circuit, and use the overload to protect the motor from overload. You can use a combination MCCB for the complete protection provided it is of the correct type and is adjustable to the nominal motor current.

In the UK our regulations state that all motors above 0.37kW must have overload protection, I imagine your regulations will be similar.

Yes, but, remember BS7671 is irrelevant when it comes to machiney.
110.2,xi