Motor Protections of Firewater pump motor

[Sajivarghese]

Are there any special considerations in designing the electrical protection of motors driving Firewater pumps (NFPA design)? Is there any practice of providing only minimum protections for these motors? (only overcurrent / earth fault in place of comprehensive protection including locked rotor / negative phase sequence / stalling / unbalance / single phasing / thermal overload, etc.)

 

[itsmoked]

Protection? We doan need no stink'in protection!


I believe any protection is contrary to the spirit of run-to-destruction that is desired in fire systems. But you should certainly get a hold of the NFPA codes if you're going to design to them. They spell it out pretty clearly.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Sajivarghese]

itsmoked,

Please pardon my ignorance.

1. I see in NFPA about provision of overcurrent protection (clause 10.4.3.3) as well as locked rotor overcurrent protection (clause 10.4.4)That is why, I was confused.

2. Me too have heard about run-to-destruction philosophy. But does NFPA say that it is a must anywhere? My doubt is regarding routine test run of the firewater pumps. During one of those test runs, isn't there a chance of motor burning if there is no protection?

Please enlighten me..... Thanks in advance..

Regards,
Saji

 

[rbulsara]

NEC (NFPA 70) Article 695 covers all you need to know about designing a Fire Pump motor circuit and protection.

Rafiq Bulsara

http://www.srengineersct.com

 

[itsmoked]

There's really a lot in there.. An example is seen here: thread184-74925

Here's another snippet.

http://ecmweb.com/nec/code-basics/electric_code_basics_17/

If you are doing the design you need the code in your hand..

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Sajivarghese]

Thanks a lot....... rbulsara & itsmoked. NFPA 70 cleared all my doubts.

Regards,

Saji