Do you guys ever use Programmable Logic Controllers (PLCs)?
By - njs0002
The SEL RTAC is about as close to a normal every day PLC as I use when it comes to the actual electrical stuff. Some of my subs have a AB PLC for monitoring room temperatures, battery voltages, controlling a sump pumps, etc. I'm in heavy industry though, not public utilities.
Traditional PLCs? Not really. I've seen a few transit companies use them for SCADA but 1) they're getting rid of them and 2) the in-house SCADA guys handle them.
Plenty of SEL RTACs and Novatechs for RTUs. Not really sure why, but utilities (that I've seen) just don't use traditional PLCs.
Traditional PLCs just don't offer any benefits for substations, since automation generally isn't needed. Now inside generation plants PLCs are heavily used.
But still in power plants it’s usually a DCS that interfaces with the electrical equipment. Plenty of PLCs for other equipment on dedicated skids, like boilers and compressors though.
I guess it depends on the generator and how modern it is, but modern or updated hydro plants and all supporting electrical equipment is nearly all controlled by PLCs to the point that you just hit the green start button and the PLC handles everything else, including trips.
4 of our Peakers are controlled almost solely using PLC's
I see RTACs, old AB SLC and some Opto 22 stuff. Most is simple I/O and 0-1/4-20mA analog stuff. There are a few installations were the PLC will handle the Auto Transfer Scheme.
As substations are upgraded, a new front end like an Orion LX may be added to the AB or Opto stuff, mainly for additional communications with the relays and security.
I think the logic is pretty light, or straightforward in a sub, compared to say a manufacturing facility.
I see a lot of RTACs being mentioned but I have only ever seen them used to pass information from relays to the SCADA. RTUs are used for control of the station but not automated. I haven't seen any RTACs used for automation.
I'm not a 'substation tech' though. I'm a NETA tech so I get around. I have seen PLCs controlling switchboard in data centers more than anywhere else. Even then, they are mostly just passing controls from the HMI to operate the system or sometimes to transfer loads in response to faults.
Yes, but we are phasing them out gradually. We have the shnieder brand and use it to send points to our operations dept showing stn alarms and what not.
We have a few PLCs for switching cap banks inside the substation. Usually time of day and temperature controlled. Really uncommon though.