loss of lighting

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martim1

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Hopkinton, MA
I have a 150hp (480v) motor for use with a fire water pumping system. When we do a weekly test as soon as the motor draws I loose lighting around a few different areas. The lighting comes from different tranformers fed from the same MCC as the motor.

What causes the lighting to drop out for that brief moment? How can I correct it?
 
Sounds like you have a voltage drop problem on that feeder that is common to the fire pump and transformers. Install your data logger on the supply side of the transformer before the next test and see what the voltage drops down to during the start .
 
Where are the engineered drawings in this situation? Is the MCC the first disconnect? If your MCC is only feeding transformers only then thats OK!

I’m going to make the following assumptions;

Your completely in violation of 695.3(A)(1).

The F/P tap is in the MCC gear because the plant wanted to save some money on the install,
there is no disconnect for the fire pump at all but was installed as to the ease of the install.
Again if your MCC is only feeding transformers then thats OK!

If there is a Disconnect for the Fire pump inside the MCC then the installation is possible violation
of 695.4(B)(2) – 1 thru for 4 depending on what you have. OR back to 695.3(A)(1).

Now all of 695.5 Transformers might or might not be your out but I don’t believe this is the case
because its direct connect and not feed from a transformer.
 
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Ok so I put a power quality analizer on the feeder to fire pump controler and I am only loosing 6v (498v-492v). dont think this would drop some of the lighting. but again it is only when I run the motor is when the lighting drops out.
 
"I?m going to make the following assumptions;

Your completely in violation of 695.3(A)(1)"

i dont see the violation. an 1800amp disco to provide power to an mcc that runs a variety of equipment.


"If there is a Disconnect for the Fire pump inside the MCC then the installation is possible violation
of 695.4(B)(2) ? 1 thru for 4 depending on what you have. OR back to 695.3(A)(1)."

The disconnect is not located "within" equipment that feeds other loads
none other (1,2,4) apply


"Now all of 695.5 Transformers might or might not be your out but I don?t believe this is the case
because its direct connect and not feed from a transformer. "

my pump runs on the voltage put out by my mcc (no transformer between the disco and the equipment).

I dont see a violation.
 
cadpoint said:
Where are the engineered drawings in this situation? Is the MCC the first disconnect? If your MCC is only feeding transformers only then thats OK!

I?m going to make the following assumptions;

Your completely in violation of 695.3(A)(1).

The F/P tap is in the MCC gear because the plant wanted to save some money on the install,
there is no disconnect for the fire pump at all but was installed as to the ease of the install.
Again if your MCC is only feeding transformers then thats OK!

If there is a Disconnect for the Fire pump inside the MCC then the installation is possible violation
of 695.4(B)(2) ? 1 thru for 4 depending on what you have. OR back to 695.3(A)(1).

Now all of 695.5 Transformers might or might not be your out but I don?t believe this is the case
because its direct connect and not feed from a transformer.
Click to expand...




You sure made alot of assumptions
 
martim1 said:
Ok so I put a power quality analizer on the feeder to fire pump controler and I am only loosing 6v (498v-492v). dont think this would drop some of the lighting. but again it is only when I run the motor is when the lighting drops out.
Click to expand...


Check the voltage at the lights themselves. It may be a poor connection in the lighting circuit that is causing a voltage drop enough to extinghish the arc.
 
martim1 said:
Ok so I put a power quality analizer on the feeder to fire pump controler and I am only loosing 6v (498v-492v). dont think this would drop some of the lighting. but again it is only when I run the motor is when the lighting drops out.
Click to expand...

Is this on startup? or when running? If on startup with a 150 hp motor, someone has done a good job on the engineering. ie;transformer size, wire size ect. that amount of voltage drop on startup is real good. Or is it using a freq drive?
 
the voltage loss is on start up. the voltage regulates after approx. 6sec.
I will check at the circuit breaker wehn I get t he chance. (pretty busy with my PM's)
 
Tell us what exactly you have as to the size the make and model and type MCC equipment tell use of the first disconnect and tell us what’s on the 6 throws.

Then no assumptions will be made! :)

my pump runs on the voltage put out by my mcc (no transformer between the disco and the equipment).

I dont see a violation.
Click to expand...
 
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