From: Andy Peters
Sent: Tue Mar 17 16:38:09 2020
To: Gerald Fisher
Subject: FW: Plant Power
Importance: Normal
Attachments: power at the wtp.png; power bump 2-24-20-10_01am.png; power bump 2-25-20-06_30.png; PPCP fail.csv; Gerald, the power situation at the Water Plant is explained below. I don’t think we are getting overly dirty power from PGE, they aren’t going to blow up our equipment. But let me know what you think after looking at a few of these graphs. Andy From: Andy Peters Sent: Tuesday, March 17, 2020 4:37 PM To: Ryan Hepler <rhepler@cityofmolalla.com>; Jeff Mccrum <jmccrum@cityofmolalla.com> Subject: RE: Plant Power PS, for our collective understanding: the dark green line is INSTANTANEOUS VOLTAGE data logged down 1/60th of a second. The Light Green Line is the Average voltage, ie, what you would see on your volt meter. The Pink Line is current, so the spikes are when your pumps ramp up. PGE is suppose to maintain the green lines on all phases to withing 30% of each other. That’s called “balance”. Andy From: Andy Peters Sent: Tuesday, March 17, 2020 4:29 PM To: Ryan Hepler <rhepler@cityofmolalla.com>; Jeff Mccrum <jmccrum@cityofmolalla.com> Subject: Plant Power Gents, after talks with Steve Isaak with PGE here is what we have: at least the two alarms we explored were due to PGE’s power dropping on leg 2. This was tough for Steve to see at first because of timestamp offsets on his equipment. Steve explained that PGE strives to provide instantaneous power (the dark green line) of +- 5% from 480v. You can see that on 2/25 at 6:30am leg 2 dropped to 448v, which triggered our alarm. This is a drop of 6.6% from 480v, so technically outside the desired range PGE tries for. But they are pretty quick bumps and Steve wasn’t too concerned about them unless they were to start happening every day. Our motors should all by UL rated, which means they are designed to take a phase bump of 10%. Which is more than the 6.6% we saw on 2/25 and the 5.6% drop we saw on 2/24 (graphs attached). It’s likely the westech logic is throwing the alarm on a 5% phase voltage drop. One answer could be to increase that to 8% if possible, which will still protect our pumps, but also allow PGE breathing room. The three second delay we put on is an okay for stopping the alarm, but if you lost a leg for 3 seconds before the scada relieved the pumps we could be whipsawing the pumps outside their UL tolerances. Steve said it’s also possible these new bumps are due to construction at the Molalla substation, where they’ve been swapping things over to make the tie ins for the new solar plant South of town. If you can tell me the first day you started seeing this problem then he can check with their crews to see if times match up. Is this enough info for you guys to make adjustments? I’ll pass this info on to Gerald. Respectfully, Andy Peters City of Molalla Public Works Operations Supervisor (503) 829-6855 x220 Cell: 503-793-0507 117 N Molalla Ave Molalla, OR 97038