# Retrofitting MV switchgear



## em158 (Jul 7, 2016)

I am replacing GE Multilin relays in 80's vintage GE 13kv switchgear. Installing new relays and adding test switches. Retrofit plates to accommodate both are being fabricated. I need to enlarge the existing opening in the door to install the new relays. I have used a sawzall in the past, but was wondering if anyone has an idea for quicker, cleaner, straighter cuts. Trying to minimize outage time and leave a clean, neat, not jaggedy hole. The hole will be covered by the new plate so external cosmetics won't matter.


----------



## MotoGP1199 (Aug 11, 2014)

I usually use a jig saw for that type of stuff. Much easier to control. I now keep the M12 jigsaw on my van as it works well and doesn't take up much space. I put blue painters tape on the panel before I mark my lines and the tape keeps the jig saw from scratching the paint. If needed I will clean put the burrs with a file. Dremels work well too but I find I get better looking corners with a jig saw.


----------



## splatz (May 23, 2015)

MotoGP1199 said:


> I usually use a jig saw for that type of stuff. Much easier to control. I now keep the M12 jigsaw on my van as it works well and doesn't take up much space. I put blue painters tape on the panel before I mark my lines and the tape keeps the jig saw from scratching the paint. If needed I will clean put the burrs with a file. Dremels work well too but I find I get better looking corners with a jig saw.


I tried all kinds of things cutting rectangular holes for panel meters etc., I should have just asked @MotoGP1199. I have a corded Freud that was cheap when I bought it about 25 years ago that's still awesome. 

As always a good blade helps a lot. Make sure you get an appropriate TPI for the thickness of the metal. I think it's best to use the shortest blade that will work in the material you're cutting. 





__





Metal Cutting Jig Saw Blades







www.lenoxtools.com


----------



## oldsparky52 (Feb 25, 2020)

I think the jigsaw makes sense. I like the tape idea.


----------



## joe-nwt (Mar 28, 2019)

I use duct tape. All it takes is a filing or two to go through painters tape and you have scratches. 

If I cut Multilins into a door that doesn't need a plate, I use black grommet material to dress up the side cuts. Push the grommet up against the relay and any variations in your jigsaw cut disappear.


----------



## Southeast Power (Jan 18, 2009)

We use these to cut loadcenter covers.







They also work very well if you ever have to cut any size EMT from end to end.
I have cut out large stainless steel circles with these also. The specifications say the limit is 18 gauge steel but, I have cut thicker metal with it plenty of times.
Harbor Freight has a cheaper model, just make sure you buy two of them at a time.


https://www.northerntool.com/shop/tools/product_988785_988785?cm_mmc=Google-LIA&utm_source=Google_LIA&utm_medium=Power%20Tools%20%3E%20Cutters%20%26%20Shears%20%2B%20Nibblers&utm_campaign=Milwaukee&utm_content=153415&gclid=CjwKCAiAnvj9BRA4EiwAuUMDfxiGc02oP7xBLcRgL-fhVbVwJDG1IBiIeldiloACgqfCJqbtAZQYChoC0ZMQAvD_BwE&gclsrc=aw.ds


----------



## CWL (Jul 7, 2020)

If going for precision I like to use masking tape and layout the lines in pencil. For less exact work black gorilla tape and a silver sharpy works very well.


----------



## splatz (May 23, 2015)

I like masking tape on metal just because it makes layout marks much easier. Also it leaves no residue, as long as you don't leave it on for days or weeks, and its not super strong so it won't pull off the paint when you remove it. 

Tape on the bed of the saw is a good idea too, duct tape might be better there or if you have it gaffer tape.


----------



## just the cowboy (Sep 4, 2013)

splatz said:


> I tried all kinds of things cutting rectangular holes for panel meters etc., I


They have the Knockout in the maintenance shop for panel meters. It was very expensive but I love it, I put 4 displays in in no time. Too bad I won’t have to use it again, using Panelview on all new panels


----------



## splatz (May 23, 2015)

Southeast Power said:


> We use these to cut loadcenter covers.
> 
> 
> 
> ...


I have used a nibbler and it works well. I didn't think it would work on 12 gauge stainless so that's good to know. But the jigsaw you can use a straight edge to get a perfect straight cut, and it's less than 1/10th the price.


----------



## splatz (May 23, 2015)

just the cowboy said:


> They have the Knockout in the maintenance shop for panel meters. It was very expensive but I love it, I put 4 displays in in no time. Too bad I won’t have to use it again, using Panelview on all new panels


That would be nice! I have gone the other way and try to buy meters that set on a round hole instead of square. If a panel meter company wanted to be really smart they'd make there panel meters sit on standard knockouts. I bought a carbide hole saw the size of the meters which also worked out fine.


----------



## gpop (May 14, 2018)

My weapon of choose is a hand grinder with a cutting disk but that means removing the door and taking it outside where metal dust will not be a problem.


----------



## Tonedeaf (Nov 26, 2012)

small grinder and a Dremel tool with alot of blades....use drop clothes to control metal and sparks so don't fly where they can start a fire


----------



## JRaef (Mar 23, 2009)

Plasma cutter. If you don't have one, rent one.


----------



## joe-nwt (Mar 28, 2019)

Light saber. Works every time.


----------



## paulengr (Oct 8, 2017)

For new panels you can use a grinder with cutting blades. It takes a steady hand and practice but gets into corners where jigsaws can’t go. A Sawzall is a demolition tool. It just makes a mess.


----------



## Viggmundir (Sep 13, 2019)

joe-nwt said:


> Light saber. Works every time.


Leaves melty edges... Also don't sneeze!


----------



## Southeast Power (Jan 18, 2009)

A shear or a square KO is neat and clean. I have witnessed an entire building emptied out when someone decided to use a grinder to cut out a square for a display panel.
Im not a fan of larger holesaws or other saw blades on panelboards, they make a big damn mess.


----------



## MotoGP1199 (Aug 11, 2014)

I've been looking at getting the TemCo 1/4 Din (92mm x 92mm) knockout is it fits almost all the meters I install. I just have a hard justifying the cost for something I don't do that much, and I already have tools that can do it. The price is good compared to others I've seen.









TEMCo Industrial TH0307 Square 92mm x 92mm 1/4 DIN Panel Meter Punch Dies 3.622" x 3.622" - - Amazon.com


TEMCo Industrial TH0307 Square 92mm x 92mm 1/4 DIN Panel Meter Punch Dies 3.622" x 3.622" - - Amazon.com



smile.amazon.com


----------



## gpop (May 14, 2018)

JRaef said:


> Plasma cutter. If you don't have one, rent one.



I bought a cheap cut 50 from ebay to install a few infra-red inspection windows on 25kv transformers a few years ago as a back-up to the miller plasma cutter. The install time was tight so a couple hundred bucks as a back-up wasn't that big of a deal. 
We have used and abused the cut 50 and it refuses to die. Even the mechanic like the cut 50 as no ones going to complain if they drop or abuse it. It doesn't have the quality feel of a miller or a esab but the cut quality is just as good. Normally im a tool snob but its hard to justify renting a machine when i can buy one cheaper.


----------



## em158 (Jul 7, 2016)

Luckily we just have extend the existing hole the Multilin is currently in, probably with a jigsaw. Door can't come off, outage time has to be minimal. New relays and test switches will be mounted, pre-wired, programmed and tested in the retrofit plate prior to outage day. 80% of the existing wiring will be relugged and reused. I'll just move the CT/PT inputs from the old relay to the test switch while my real electrician extends the hole and drills holes for mounting hardware. I'll report back in a week or so to let you know how smoothly, or not, the first one turns out.


----------



## paulengr (Oct 8, 2017)

If you have a choice use an SEL 710 instead of a Multilin. The motor thermal model is much better, and intuitive the diagnostics make Multilina feel like eutectic relays, reliability puts GE to shame but then so does a eutectic, and programming is 100% flexible. Only downside is there is a STEEP learning curve programming wise. For Mulrilin conversions they make bezel plate adapters so no cutting at all. The only conversion hassle is to work correctly the relay needs to have a spare aux contact hooked to it. On the old 239/269 the 749M is a better fit. Not as nice as the 710 but half the price. The 710 is already almost half the price of a 369.


----------



## em158 (Jul 7, 2016)

paulengr said:


> If you have a choice use an SEL 710 instead of a Multilin. The motor thermal model is much better, and intuitive the diagnostics make Multilina feel like eutectic relays, reliability puts GE to shame but then so does a eutectic, and programming is 100% flexible. Only downside is there is a STEEP learning curve programming wise. For Mulrilin conversions they make bezel plate adapters so no cutting at all. The only conversion hassle is to work correctly the relay needs to have a spare aux contact hooked to it. On the old 239/269 the 749M is a better fit. Not as nice as the 710 but half the price. The 710 is already almost half the price of a 369.


GE Multilin is quickly going away. Products are basically all discontinued and no longer supported. The newer Series 8 GE relays are failing at a rate that I have never seen before in any other brand. 

The biggest learning curve when dealing with SEL is to stop thinking like an electromechanical relay tech.(GE spoke in old guy terms I could understand) and to learn SEL's relay word bits. They all do the same thing, but it's like speaking a different language. 

There will be a HUGE market in replacing Multilins for the next decade.


----------



## paulengr (Oct 8, 2017)

SEL “way” (also Basler and others) is like a PLC. All inputs go to the protection relay. Aux contacts, voltages, currents, push buttons or other on/off signals, etc. All outputs are the same way. Then you write logic statements to “wire” up everything. You CAN use a graphical editor (like PLC logic) for this but I don’t know anyone that does.

SEL provides about 99% of the logic pre-built. Only time you need something highly customized is say a main-tie-main scheme (they give you this as an example) or say sequencing contactors on a wound rotor motor. It is that easy once you “get” it.

The downside if you want to call it that is the default logic it comes with uses every bell and whistle. So it will use negative sequence tripping for instance. Although conceptually I like the concept, try explaining to an electrician how to troubleshoot a negative sequence fault. So MY defaults include turning off anything not used which is a lot.


----------

