Electric Fire Water Pump Feeder design

[RajT]

We are requred to provide a 6.6kV DOL vacuum contactor feeder to a 500kW motor forming part of a Fire water pump package.

I understand that the NEC or some other standards require that the contactor design must be of a mechanically latched type vs the conventional magnetically held type.
I can see the logic in the application but can any one guide me to the correct "standard and the clause" which defines this requirement.

 

[dpc]

NFPA 20.

http://www.nfpa.org

 

[rbulsara]

That is some fire pump!!! where is this?

 

[RajT]

Many thanks.

 

[RajT]

rbulsara,

The FWP is on a new build FPSO . Actually there are two units with the larger unit rated at 1300KW DOL at 6.6 KV

 

[Noway2]

I am not aware of this requirement regarding the motor contactors, however you may be confusing this with the emergency start circuit. In addition to the automatic electrical operation, there needs to be an emergency start handle that is able to be mechanically held in place. This emergency start usually pushes the armature of the main across the line contact applying line voltage directly to the motor. There is an additional requirement that says in a low voltage system (under 600Vac) that the contact coil must be powered by line voltage and not by reduced voltage such as provided by a transformer.


The NFPA-20 document is the ultimate Bible governing the controller design and operation. In addition to this document, though, UL and FM (Factory Mututal) have their own sets of requirements that go above and beyond the requirements spelled out in 20.