protection for metering pump motor_40Watt, 240V, 1-phase

[RRaghunath]

The pump is part of water treatment system in the power plant. Could some one please tell me,

Is it necessary to provide protection (other than short circuit protection accorded by fuses) for such a small motor.

What are the options available.

and

what is the industry practice.

Thanks in anticipation.

 

[EEIre]

It would be normal practise to use an MCB or fuses to provide short circuit protection. Most likely the pump will be controlled by a PLC or the like so you will need a contactor to facilitate this. So you may as well provide an overload on the contactor.

Regards

Sean

 

[RRaghunath]

Thanks Seanmx.

You are right the motor is to be controlled from PLC and I agree the cost of bi-metal OL relay would not be much.

But availability of OL relay for such small current rating appears to be a problem with some of the vendors.

Any comment.

Thanks once again for the response and I appreciate if you could quote any projects / practice for reference.

 

[EEIre]

Siemens for example have an overload relay available with current settings from 0.1 to 0.4A which should do the trick here. This is a three pole device so you would need to connect two of the poles in series to use on a single phase motor.

Alternatively you could consider using a din rail mounted single phase VSD, speed control is sometimes a useful facility for metering pumps. So as well as speed control you would get overload protection and a means to interface with your control system. This is the solution I have seen mostly in my experience.