Nuisance tripping of 80 amp CB?

[69boss302]

Re: Nuisance tripping of 80 amp CB?

Originally posted by charlie tuna:
musty,
insulation break on a wire inside a raceway doesn't last long -- it welds itself to the raceway!

I had wires on a 150HP Nitrogen Compressor Motor that went better than a year chaffed inside the conduit from the pull, couldn't even notice it in any of the fittings. It was very intermittent, would trip the breaker about 5 times every 3 or 4 weeks and then run fine. Kept going that way for a year. They replaced the motor once, the breaker three times, and it never smoked anything, just got lucky to find it when they went to change the motor the second time for no real reason but to try it again, and when they meggered the wires back to the breaker this time they were grounded. They never welded together or to the pipe, slid right out when they went to replace them.

 

[Mustangx3]

Re: Nuisance tripping of 80 amp CB?

Let me try to answer the last few questions all together...
The cooling tower was installed in February (when the elevator problem showed up hhhhmmmm?)
Power comes from a nearby transformer in a parking lot basically, then into the building to the switch panel which supplies about 30% of the building. Our elevator is off the same main feeder as the cooling tower. We did put new wire into the existing conduit for the elevator when the new circuit breakers were installed.
As for the air compressor, I'll let them know to check on the caps (hasn't been done to my knowledge yet, thanks!).
Since EVERYONE is still focused on the elevator "problem" they haven't (and most likely won't) check the wires in the newly installed cooling tower. The tower is back up and running, voltage sags haven't been seen yet but we're monitoring 24/7. We fully expect to see the sags again and (I hate to say it) smoke the new cooling tower AGAIN. THEN maybe they will check their wires, etc.

 

[Mustangx3]

Re: Nuisance tripping of 80 amp CB?

Saga continues... the building has had several fire alarms that they can't determine the cause for. The alarm tech dared to utter the statement "voltage sags could be freaking out the fire alarm system". The building personnel are so gun shy after the roof top cooling tower smoke job that the exit pretty quick when the alarms go off now days! Elevator now has the 125 amp CB's installed and hasn't tripped yet but we now have a new condition that we haven't seen before. When the power sag occurs the elevator computer would stop then instantly re-start the 40 horse motor and likely cause tripping of the 80 amp breaker. Now that the 125 amp is installed the problem has "changed"... Since the CB doesn't trip anymore, the computer now looses "where" the elevator is so it stops the elevator in mid travel then returns it to the 1st floor in order to "re-set" its location in software. This is what it is supposed to do if there is a lost of communication. What's funny (or not) is that when the elevator is traveling up at 175 fpm then STOPS instantly you get quite the negative G's! (I'm floating!) We have decided to put a "toll" box outside to charge 50 cents for the E ticket ride!!
Anyway, the building officer doesn't exactly see the operation as normal so the investigation continues... I'm sure more will follow.

 

[69boss302]

Re: Nuisance tripping of 80 amp CB?

Thanks for all the updates Mustang. It's always interesting to see what happens when they start "Easter eggin" as I call it. Treat the symptom and just seem's like another problem comes up. Just wait till "they" actually find the problem because it burned up and start patting themselves on the back.

Please excuse my cynicism, been there to many times.

 

[Mustangx3]

Re: Nuisance tripping of 80 amp CB?

Well, the latest is that we installed a UPS to power the 120 vac. Figured since the reverse phase detector (and low voltage detector) didn't like to play with the 330 vac sags we should install a UPS and bypass the RPD all together. Actually I think this will work since it will keep the computer powered up during a power loss and smooth out the sags in the normal day time. The RPD couldn't be set for lower than 350 vac sags so when the 330 vac sags occured it must have shut down the power to the controller. Only time will tell but "in theory" it just might work. Oh, forget why we have to do this after it has worked fine for 12 years and NOW needs a UPS...

 

[69boss302]

Re: Nuisance tripping of 80 amp CB?

Cure a symptom while the problem still lurks about. I always like that plan too.

 

[charlie tuna]

Re: Nuisance tripping of 80 amp CB?

mustang,
normally in office buildings the elevators are fed from the emergency power system. and a cooling tower is not normally fed from the emergency power system????? when the cooling tower was connected to the elevator feeder was this considered???

 

[Mustangx3]

Re: Nuisance tripping of 80 amp CB?

The building doesn't have a back up power system (like a genset or anything). When power is lost... it's LOST. People do have small UPS's on their computers but that's a choice they make (and usually have to pay for themselves). System has been operational for a couple days now and works but it's more likely (in my opinion) that it works because the Reverse Phase Detector/low voltage detector is bypassed and NOT that a UPS is online. Now we are hooking up our Powersight 3000 monitor again... we call this a "M.U.D." run, (more useless data) for the powers that be. Engineers want to see the UPS in action??? Hmmm...

 

[catchtwentytwo]

Re: Nuisance tripping of 80 amp CB?

There hasn't been any blinking lights or dimming that we are told, quite a bit of the systems are on huge UPS too.

I thought there was one large UPS system (as you metioned earlier), not small ones for individual computers. How is the "large" one reacting?

 

[Mustangx3]

Re: Nuisance tripping of 80 amp CB?

The larger building system UPS is for some critical test equipment that must run for several days (or weeks) during the "testing period". If power goes out (which is often) the tests would be ruined and have to start over. That's what most of the buildings purpose is and why the huge UPS is there. The "normal" stuff like personal computers, elevator and typical office building stuff isn't UPS protected. That big UPS logs the power outages (and alarms) of course but it can "run through" a power sag without "going on the batteries". They use it for smoothing power and providing constant voltage to the special testing equipment. The documentation states that the large UPS can handle over 1 sec. of power loss per leg without switching to batteries while keeping voltage totally stable. It does log (but not alarm) the sags (and sees them just as our Powersight does). So far so good, it has run all week without a problem and we recorded several sags on different phases during that period. I still suspect that bypassing the RPD did the trick... at least for now...??

 

[Mustangx3]

Re: Nuisance tripping of 80 amp CB?

Well, I guess I can report that the source of the power sags has be traced and verified. It comes straight from Bonneville Dam on the Columbia River (between Oregon/Washington borders). The "BPA" (Bonneville Power Administration) has provided us with a letter saying that they have a 5-20% sag for about 50-100ms as part of their natural operations. What we are seeing is "natural". The sags to 330vac are "natural" and sensitive equipment should be protected for this "naturally occuring event". I guess when a salmon gets sucked through the turbines it burps. Apparently this will end my saga since BPA can't provide stable power (less than 20% variances) we will be living on UPS's. Guess when I told the the source of the sags was "upstream from the elevator" they took it literally to mean "UPSTREAM".