SEL 2431 Voltage Regulator Control

[matanuska11]

I am looking for info on Schweitzer 2431 controllers, specifically for a Siemens JFR voltage regulator. I have three units on a three phase distribution system, being feed from reverse(source side voltage is supplied onto the L bushing, load voltage on the S bushing)with the controller mode set to BiDirectional, intending to see being fed from either S or the L bushing on the regulator. The controllers are all maintaining a Auto-INhibit status in the BI-DIR mode, but in a LockedReverse mode, the units regulate. Mind you, I have (company I work for) another SEL Voltage regulator on another distribution line that functions just fine in this mode. the settings are basically the same, except the unit that functions ok, is newer and it's kVA rating is a little bit larger. I appreciate any info in relation to this, thanks.

 

[HornTootinEE]

mantanuska-

Maybe you have done this stuff, but I've run into funky issues myself with a SEL retrofit on a Siemens regulator, so here are a few things to consider:

Have you looked in the manual as to what might cause the Auto Inhibit? With an SEL (or any reg control for that matter), it can be some small little default difference between two generations of controls that will get you on something like that. The advantage of Schweitzer Engineering is that their manuals are almost over detailed. Some little default logic value throwing the Auto Inhibit problem?

Another issue may be the PT input. I know the Siemens regs have a different PT scheme than GE or Cooper-I don't remember the details off the top of my head anymore. Is the PT plug position wired to the wrong control input, or the internal PT setting incorrect? I've run into that before on a Siemens retrofit that made some goofy issues crop up. The SEL field set up or retrofit guides should have some details on this connection.

Are you using Line Drop Compensation? If so, is there an R, X, or Time Delay value missing for bi-directional mode that is causing the control have a fit?

Have you contacted your regional SEL Application Engineer? Those guys are usually good at either helping you or knowing another SEL person who can help you with that particular control. I will say that regulator controls are not their specialty, so they may have to work to find someone who knows something, but they will help you.

Did I mention I hate Siemens regulators?

 

[matanuska11]

HornTootinEE,
Thank you for the reply. I have covered most of the issues you mentioned: AutoINhibit is asserted when no current is sensed, IL, current is measured at zero, resulting in the NO torque region. And we captured the metering of each unit and sure enough, we are unable to get the units to sense the load. We I mean SEL engineer and I. I have changed the CT polarity in the settings and reversed them and the PT also, not at the same time because it would still see it at non reverse.
I haven't used the LDC in any regulator in our system either, and I might just be adding fuel to the fire in this sense. I did finally contact Siemens about this issue, and noting we had a SEL controllers in the Siemens product, they weren't able to spend a whole lot of time troubleshooting, but he mentioned that these regs were almost thirty years old that perhaps the standard wiring was not capable for these newer controllers. I am looking to jumper the PT output next, but waiting to hear back from SEL and verify all wiring connections. Thanks again, I appreciate your insight.

 

[HornTootinEE]

Yeah, LDC would be adding fuel to the fire, so it helps you aren't using it in this case.

Could the CT leads in the tank of the regulator be disconnected somehow? Thats a possibility. If that reg was ever untanked and had the CT leads disconnected for some reason (i.e. change out a motor capacitor), it could be they weren't ever reconnected.

Or you may have a shorting switch closed somewhere. I don't think Siemens regs have a knife blade shorting switch in the control cabinet as that is supposed to work on the plug they use, but you never know. Something to check out.

Good luck

 

[matanuska11]

The possibility is that the CT's are disconnected in the tank. It is the last step I wanted to take, but really it is the next one. I appreciate your insight, take care, HornTootinEE