New FirePumps

[JimmyJunior]

Recently our engineering group purchased and started installling 4 firepump assemblies in our utilities plant. Each of these assemblies consists of a firepump controller, a pump and a 250HP motor. The decision to replace the older firepumps was made because the older pumps were installed in 1962 and the pumps had started having problems. Each older pump was driven by a GE 250HP motor. In 2003 a new 2400kW (800kW ea standby) Kohler parallel, random access E/G system was installed. Prior to purchasing the E/G system
was modeled as were the 4 older firepumps using factory data (inertia, torque curves, etc). Static and dynamic motor starting was done under various operational scenarios using both the normal source and the E/G system. The modeling reavealed various problems that were corrected with the E/G manufacturer. The E/G system when finally installed and test ran all the commissioning tests without a hitch.

No such modeling and motor starting simulations were performed or allowed to be performed. The logic used was that as long as the motors were the same horsepower then everything would work as before.

Comments please.

 

[MikeHalloran]

Well, _if_ the assertion that bothers you (and me) is true, then it should be no big deal at all to re- run the commissioning tests with the new motors.

... Just to keep everyone honest.



Mike Halloran
Pembroke Pines, FL, USA

 

[jraef]

Seems to me that there are a few major assumptions there. And how is it that we spell that word in sigular form?

ASS - U - me

Are the motor designs exactly the same? What if the starting current is higher?
What if the motor starting torque is lower, making the acceleration time longer (very possible with newer high efficiency motors)?
Is the installation exactly the same?
What if there are fewer cables with more impedance?

Fire pump systems seem like bad places to do the ass-u-me thing.

 

[ScottyUK]

Is the person who decided that modelling was unnecessary prepared to defend that decision in court if the system falls over during a real emergency and someone is hurt or killed as a consequence of the firefighting system failing?

What do the insurers think about an unproven, un-designed firefighting system? Is the site's insurance even valid under these circumstances?


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If we learn from our mistakes I'm getting a great education!