Caught on Tape!-
Upstream voltage Sag proves culprit in Electrical Equipment Mystery
“It was surprising to [the utility engineers] and me that with PQubes monitoring I can tell down to the thousandth of a second, exactly what my electricity is doing. I have graphs that show exactly what time a car crashed into power poles down the road. I know exactly when the power was rerouted to another circuit and what it did to affect my machines.”
Composiflex Maintenance Supervisor
Composiflex, a composites manufacturing plant in Pennsylvania, had an electrical mystery on their hands.
The situation was not only dangerous but expensive: $50,000 worth of equipment damage a year, and that much more lost in downtime.
“When I was first got here, we were blowing up amplifiers and circuit boards like they [were] candy. The current and voltage spikes were blowing holes through ¼” aluminum. End caps on buss bars were blown off. Circuit boards had 8” of wire race blown off. Fuses were blowing like popcorn all over. I was nervous opening any disconnect box as several times they blew when the doors were open. I was, shall we say, gun shy.” — Dan Claxton
Dan suspected bad power by the utility but had no way of proving it.
What he needed was data; ideally, a picture of the power, over an extended period, that would capture any voltage spikes or dips the moment they occurred.
With its low price and high level of precision, the PQube (www.pqube.com) seemed like the perfect instrument to provide this kind of data. It snapped on the DIN-rail inside the main panel and could be read remotely with an optional ethernet module, without the need for software.
As soon as the installation was completed, the PQube began to sending graphs to Dan’s email.
“[The utility guys] were very helpful once they realized the problem was real. They have gone out of their way to fix all issues. No one ever wants to take the blame but all I wanted was answers so we c
ould fix the
problem. PQube allows me to see it is not my internal problem. I was able to show the energy supplier that it was coming from them and now my problems appear to be gone. I believe the engineers were happy to see the reports because it helped them fix the problem.”
- At 23:55 pm on March 17, Dan receives an email on his smartphone,
with a chart, alerting him that a voltage sag occurred. The waveform coming directly from the PQube shows a 1.8 sec, 25% voltage sag on the L1-L2 and L3-L1 lines.
- L1-N voltage sags even more, down 50%,, indicating a L1-Earth fault somewhere upstream from the monitoring location.
- As a result of the sag between L1 and N, current on L1 drops, causing
L2 and L3 current to shoot up.
4. A protection device upstream takes 1.8 seconds to trip and remove
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This article republished with permission from our principle www.powerstandards.com