What types of different relaying are recommended for a medium voltage electric fire pump? How to determine the overcurrent protection for such motors?

For the fire pump the recommended protections are:

Overload, overcurrent, earth fault and negative phase sequence or broken conductor ( the last is for an open phase as for this type of unsymmetrical fault it may not be detected by other types of protection).

How to determine the overcurrent protection?

It may just be over the overload protection (which may be made to last for long time) but with minimum time.