electronics burning out

[jimingram]

I was sent to a newer building in a Minneapolis suburb to check out a problem with electronic boards failing.

The building has an underground parking garage, retail space on the ground floor, with condos on the the three upper floors. It is located in the downtown area of the city.

There are separate services for the retail spaces and the condos. An elevator serves the condos from its service. Both services are 120/208, 4W and are served from the same transformer.

One of the retail tenants has a restaurant. He told me he has lost the control board on his "WIFI" and his computer cash register "POS" has had trouble operating. The computer people tell him the problem is not with the computer.
He has decorative outside lights which are incandescent. At different times he's had different multiple lamps burn out simuoustaneously.
The owner has observed no dimming or blinking lights.
He has a 400 amp, 3 phase, 4W feeder to his unit. It has a 320 amp meter without CTs in the meter bank. How good of an idea is that meter on a commercial load? I wasn't able to check the load at peak time but I know it will high.

The mechancial contractor has had trouble with a control board also. He told me the unit he uses for the cooling tower is reliable and this building is the only one he's had to replace. He has installed a surge protector but says it hasn't done any good. He hasn't burned out another board but says when a thunderstorm goes through it knocks it offline and everything shuts down. He has to come out and reset it to bring the cooling back online. The HVAC system is fed from the the condos service.

I have unconfirmed information that some of the condo tenants have had electronic boards on their tvs burn out.

I did a visual check on the service equipment and ground. I saw nothing out of the unusual.

I would appreciate any ideas on what to do next and what could be causing the problem.

Jim

 

[sparky_magoo]

Re: electronics burning out

Do you have three-phase branch cicuits sharing a common nuetral? Is it possible that unbalanced loads are causing the nuetral conductor to be over-loaded by triplens harmonics? The distortion caused by this situation might cause your electronic boards to crash.

 

[petersonra]

Re: electronics burning out

what I don't understand is how an overloaded neutral could cause that kind of damage. most stuff does not care much if the voltage supplied to it drops a little.

pos equipment is often cheap junk, as are HVAC controls, so I am not too suprised that any kind of power disturbance would cause that kind of equipment to fail.

 

[charlie tuna]

Re: electronics burning out

jim,
three things strike me in your question, "older part of the city" --- "three stories high" --- "elevator"....................
many of the power grids in cities that are now undergoing "residential rebuilding" do not have sufficient capacity for the upcoming construction. seems like the grid is only upgraded as it becomes necessary. this causes voltage fluctuations --both high and low?

since the building is only three stories high, i am assuming it has hydraulic elevators. hydraulic elevators cause major current draws as starting loads! and they sometimes cause a high surge as they cycle "off"!
if you have a weak power network and couple it to a heavily loaded service(apartments)--then add the starting load of the hydraulic elevator --- you might have a low voltage problem?

i would take two of my metrosonic data loggers and program them to monitor the current and voltage at both the resturant outlet and the mechanical contractor's control circuit for one week --then down load that information to my computer and print out graphs and know whats happening!

if i didn't have the data loggers -- then i would recommend the installation of two ($120.00) ups units(with battery back up). one on the cash register and the other on the a/c control unit. the mechanical contractor should have installed one as soon as he had to replace the first control board.

 

[pierre]

Re: electronics burning out

"i would take two of my metrosonic data loggers and program them to monitor the current and voltage at both the resturant outlet and the mechanical contractor's control circuit for one week --then down load that information to my computer and print out graphs and know whats happening!

if i didn't have the data loggers -- then i would recommend the installation of two ($120.00) ups units(with battery back up). one on the cash register and the other on the a/c control unit. the mechanical contractor should have installed one as soon as he had to replace the first control board."


I like this response as it gives two legimate solutions based on cost/value to the customer.