Fire Pump Motor burning out on loss of phase

[CanuckEngineer]

Hello All,

I have a client I am working for who on two separate occasions (within about 6 months) has had to replace a burnt out Fire Sprinkler Pump.

The pump supplier technician said the motor burnt out on a loss of one phase for an extended period.

Reviewing the upstream ATS controller (TornaTech supplier) it sure enough shows a loss of phase for an extended period.

My questions before calling for an expensive power analysis study do you guys have any comments on what may have caused the loss of phase condition? Upstream transformer winding problem? utility problem?, etc.

Thanks again for your help.

Regards,

RK.

 

[CanuckEngineer]

For those of you who may be asking.

The power transformer secondary is a Y connection with the neutral solidly grounded to earth.

Thanks,

RK.

 

[jraef]

Your attachment has an error in it.

Are the sump pumps 3 phase or single phase?

Another potential issue is the control of the sump pumps. Simple is best, but hardly anyone does simple any more. So if you have some sort of overly complicated electronic system controlling the sump levels, and during a voltage transient event and/or ATS transfer that controller goes haywire, it might be rapidly cycling your sump pumps causing them to fail prematurely. I was involved in one where they had an electronic pressure transducer in the sump, feeding a controller that decided when to turn the pump on and off, with the added capability of transmitting the sump level to the BMS. They never bothered to connect it to the BMS, so that was a complete waste, but I was able to use that capability to record what the sump level controller was thinking. During some sort of transient voltage events, the controller would temporarily get a false high signal from the transducer (the value would go to 65,536 meters, a suspicious value indicating all high bits in a 16 bit A/D converter), which caused the pump to turn on, even though there was no water actually in the sump. Then in a few seconds, the value would clear, the real value would show up, and the pump would immediately turn off. That is NOT good for a motor if it happens over and over, which it did in that case. Their solution was to find the device that was causing the noise on the line that was fouling up the sump controller, which I don't think ever happened (I left after finding the problem). I would have yanked it out and just put in a freaking float switch...


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[CanuckEngineer]

Thanks jraef.

Great info.

I will repost the attachment shortly, hopefully no errors this time.

Regards,

RK.

 

[CanuckEngineer]

Here is the attachment reposted.

Thanks,

RK.

 

[waross]

Is the utility using newer electronic KWHr meters?
In the poorest country in Central America The power company engineers were able to program the electronic KWHr meters to provide readings at 15 minutes. This was a free service. I would make a request and they would send a technician out to download the information from the meter. I would then take in a floppy disk and get a month or more of readings taken at 15 minute intervals.
Are the transformer primaries star or delta?
Are you in a city or out on the end of a long distribution line?
I have encountered situations where the line to neutral voltages looked good, but the phase angles were off and the line to line voltages were off. This is hard on motors. The back EMF of a motor is equal line to line and the phase angles are good. That is why a small unbalance in voltage will cause a large unbalance in current.
A wye:wye transformer bank will pass on good line to neutral voltages and bad line to line voltages.
A delta:wye transformer will mix things up a bit.
Still can't open the attachment and see what the values look like.
Yours
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[KuanYau]

CanuckEngineer (Electrical)(OP)

1. Assuming "The pump supplier technician said the motor burnt out on a loss of one phase for an extended period" is correct, then the problem is within your plant, not the utility.
The problem can be resolved by taking following actions:

A. Replace all (up-stream and down-stream) [three-phase fuses by (three-pole) breakers].
This will [eradicate for good loss of one phase problem] caused by blowing of a fuse in a three-phase system.
Note: A three-pole breaker [opens or closes all three-phases simultaneously]. This feature eradicates single-phasing (frequently occurred in systems using fuses) for good.

B. Replace the motor thermal over-load relay with a [phase failure-sensitive] motor protection relay.
Note:1. This device is [similar to the normal thermal over-load relay] but with [additional phase failure-sensing feature]. [In the event of single-phasing, it will trip at 85% of the three-phase tripping current].
2. These phase failure-sensitive over-loads are similar in size as that of the normal over-loads and are produced by all major manufacturers in Europe.

 

[CanuckEngineer]

Thanks Waross and KuanYau for your input.

Waross, I am not sure why the attachment is not coming up, it came up before in another thread.

Here are the answers to some of your questions:

Are the transformer primaries star or delta? Delta, 95% of Ontario-Canada primaries (for non industrial buildings) are delta.

Are you in a city or out on the end of a long distribution line? In a large commercialized suburb (not quite the downtown core).

I will work on getting more detailed 15 minute interval readings.

Much thanks,

RK.

 

[CanuckEngineer]

Repost, retry.

 

[CanuckEngineer]

Repost, attachment retry, again.

 

[CanuckEngineer]

To the site moderator:

Can you see why my file attachment is not uploading via Engineering.com

When I click on link submission it says everything is successful.

Regards,

RK.

 

[ScottyUK]

At a guess, the " ," and " & " characters in the filename might be contibuting to the problem. Try again with a simple filename?

 

[CanuckEngineer]

Thanks Scotty.

I will try right now.

 

[CanuckEngineer]

Re-post of file attachment.

 

[CanuckEngineer]

Repost

 

[CanuckEngineer]

Success!!

Thanks Scotty I will remember that for future.

File has successfully attached on my last post.

Regards,

RK.