Fire Pump Controller (VFD)

[ElecDar]

We have water pumps serving combined water\fire network.
In the Code (NFPA) the fire controller is allowed to start a motor while limiting the current drawn by the motor, the stipulation is that the starting period cannot exceed ten seconds.
My question is there any requirements in the Code which prohibit the use of a Variable Frequency Drive (VFD) as a fire pump controller?

Thanks in advance.

 

[123design]

ElecDar!

Variable frequency Drive is not allowed for the Fire pump controller. However, if you elaborate your question then I can try to answer you question in more meaningfully.

You can use DOL started or Y-Delta starter either it could be open transition or in closed transition. Selection of DOL & Y-Delta starter is based on local regulation and pump-motor rating.

 

[ElecDar]

123design, The water pumps are serving a combined water\fire network; this is the main reason for installing the VFD to modulate the pump speed during normal operation based on varying demand in the domestic water system. This combined network is also serving external fire hydrants.

I'm not sure that the VFD is not allowed by the code as fire pump controller. Actually NFPA 20 (clause 7-4.5.2) allowed for the operation of reduced voltage controllers (acceleration not to exceed 10 sec.) this is not a restriction for the VFD (unless you are referring to another clause). I’m trying to investigate the possibility of having VFD with failure mode cross line full voltage and listed for fire service.

 

[peebee]

The attached excerpt from NFPA 20 doesn't answer your question, but maybe it will help. I'd be real careful about using that VFD.

Formal Interpretation
NFPA 20
Stationary Pumps for Fire Protection
1999 Edition
Reference: Chapter 8
F.I. 83-10
Question 1: Is it the intent of NFPA 20 to require the diesel engine fire pump to reach rated speed without delay in a fire condition?
Answer: Yes.
Question 2: If “yes” to the above question, will an automatic soft start unit which will throttle engine from an idle to start to full RPM within an adjustable period of time (0-1 minute) be permitted?
Answer: No. Delaying the fire protection system response to a fire by up to one minute could result in the fire getting out of control. Response to a fire by the sprinkler system should be as quick as possible.