SymCom motor saver 500

[reagal beagal]

Here in my building, we're having an event that's causing the motor saver 500 to shunt the main breaker. The motor saver is at least 25 years old, and there are times where all the trouble indicator lights are on, and there are times when no lights are on - not even the run light, and this is when the air compressor is running. The air compressor is the only load on the MCC right now. I'm convinced it's the motor saver itself that's causing the issue. I expressed my concerns to my boss, who discussed it with his bosses, and they decided to buy a new main breaker...which did not solve the issue. Is there any way to troubleshoot the SymCom Motor Saver 500? I've looked all around our files here at work, and on the internet , but I'm not having any luck finding any literature. Any help or direction would be greatly appreciated.

 

[Little Bill]

What is a motor saver?

 

[tom baker]

I had long used Diversified SLA 440 phase monitors, they would last about ten years, then I would sen in for repairs. Eventually I called tech support, they said the capicators are good for 12 years, in service or on the shelf. I used to keep spares, but went to keeping one spare. I dated all the SLAs and didn't bother with repairs.
The diversified is a great product with a lot of options and time delays, take a look to see if they would work for you.
I am sure your issue is with the motor saver, esp it being 25 years old.

 

[zbang]

It appears to be a phase-protection relay.

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Symcom Motor Saver - 3-Phase Overload Relay/500-600V/2-800FLA/Plus

Discontinued

www.mitchellinstrument.com

https://m.littelfuse.com/~/media/pr...ls/littelfuse_protectionrelays_ii_520cp_b.pdf (which is probably close)

I'd just replace it and move on.

 

[reagal beagal]

I appreciate the responses, maybe this will give me a bit of ammo when I explain - to my boss again - why I believe it's the motor saver itself causing the problems.

 

[reagal beagal]

What is a motor saver?

From what I can tell it monitors over-voltage, under-voltage, reverse phase, voltage imbalance, and phase/frequency shift. At least there are red indicator lights for each of the things I mentioned. I'm unable to post a picture from where I am now, but they're on eBay for less than $100 lol. It monitors the three phases, and it also has a 120v control circuit that during an event will close the normally open contact, thus shunting the main breaker in my MCC. And there's also a green run indicator lamp. I've been an electrician a little over 25 years now, and I've only been working here less than a year, and I'm seeing more and more relics at this place that I've never seen before.

 

[tom baker]

How expensive is it? The diversified units were about $150.

 

[reagal beagal]

How expensive is it? The diversified units were about $150.

I'm not sure what it cost new, I believe that particular model is no longer manufactured. I've seen a couple of them on eBay in the last couple of weeks, and they're very cheap, around $100 or so.

 

[Jraef]

The Motor Saver is wired to a shunt trip on the main breaker then? Why?

If it isn’t wired to a shunt trip on the Main, then it is not the problem. It’s just monitoring the voltage, there is no load involved with it.

 

[reagal beagal]

The Motor Saver is sited yo a shunt trip on the main breaker then? Why?

If it isn’t wired to a shunt trip on the Main, then it is not the problem. It’s just monitoring the voltage, there is no load involved with it.

Bear with me as I'm new to this facility, and I work third shift weekends, so there's absolutely no one here to bounce questions off of or actually get any kind of clear answer. I have no idea why the main is shunted. It would make sense to shunt the breaker of the motor that needs protection, and not dump the entire MCC when an event occurs. The motor saver is wired to trip the shunt on the main. When an event occurs, it closes a contact inside the motor saver, which allows the 120v control circuit to shunt the main. It makes no sense to shunt the main, but that's what I'm dealing with.

 

[paulengr]

It has been a long time...

Based on your description sounds like it could be the Symcom. But if nothing is consistent not much you can do with it. The Symcom is an early advanced microprocessor overload/motor protection relay. It was a more cost competitive GE Multilin 269. The problem is there’s not much you can do if you don’t know why it tripped and the fact that is never consistent says it is probably a hardware fault. Electronics start to give you trouble anywhere from 8-10 years (electrolytic capacitors) to 15+ years (solder joint failures) so my suspicion is the Symcom is done for. So we have two problems...verifying if anything really is going on and replacing that dinosaur.

So a couple ways to go here. If you already have an overload relay then you could just eliminate the Symcom or disconnect the shunt trip so you can see what it’s doing.

Warning. Check the HP of the load. Once you get up to 500+ HP you’ve got to be more careful. On smaller motors the stator is the thermal limitation so even an old eutectic relay works. But over that size the rotor fails if you don’t shunt things down if the motor ever stalls. This is where advanced motor relays are a necessity. Even sometimes in smaller motors they are beneficial. A customer recently failed several 350 HP motors in a row simply because they had some worn out contactors that caused excessive current unbalanced. A fancy motor protection relay would have caught this and prevented damage. This was the sales pitch for the Symcoms.

Eliminating the relay leaves the question of what is going on. One option is stick a power quality meter in there. An SEL 735 (best) sets you back around $1500 as does the Schneider Powerlogic. Those are monitor only. If you can rent or have them on hand it’s not out of line to leave it there long enough to verify if anything is going on. If you don’t see anything of concern after a couple days, it was the Symcom. You could also ask a local motor shop to do an online and offline PdMA test. This gives you pretty good confidence both the motor and starter (and incoming power) are in good shape.

Or if you need to buy, in about the same price you could go with an SEL 749M as a top of the line motor protection relay that gives you tons of data for troubleshooting and free tech support and “lifetime” warranty. The learning curve is steep on SEL products. If this is your first time go with someone experienced. SEL is the PLC of relays. The advantage here is you get almost the diagnostic capabilities of the power quality meter but with the overload relay only. If you have more money a 710 is even better but I recommend those on large motors (over 1000 HP) where the cost ($2500+) is more justifiable.

If you want more advanced protection similar to the Symcom but stay in the price range of an overload relay and something less intimidating to set up you can look at the Toshiba RX relay that is private branded by multiple vendors (Benshaw, Motortronics), or the Sorecher and Schuh relays if you want something more basic. These are microprocessor relays but you get far more basic troubleshooting information.

 

[reagal beagal]

Eliminating the relay leaves the question of what is going on. One option is stick a power quality meter in there. An SEL 735 (best) sets you back around $1500 as does the Schneider Powerlogic. Those are monitor only. If you can rent or have them on hand it’s not out of line to leave it there long enough to verify if anything is going on. If you don’t see anything of concern after a couple days, it was the Symcom. You could also ask a local motor shop to do an online and offline PdMA test. This gives you pretty good confidence both the motor and starter (and incoming power) are in good shape.

Lots of great info, I appreciate it. I have a Fluke 435 on it now logging data, and so far the shunt is holding. There haven't been any odd fluctuations or any recordable events to speak of, everything I'm seeing is consistent with a small motor starting. I have a couple more bases to cover before I'm done for the night, but I'm definitely leaning towards trashing that old paperweight and bringing at least part of this building into the 21st century with a new overload relay. Maybe something that I can tie into my BAS, at least for monitoring purposes.

 

[Jraef]

The Symcom 500 is not an OL relay, it’s just an over/under voltage and phase reversal relay. Wiring it to the main for the entire MCC is asinine in my opinion. It could be that under certain circumstances, starting the compressor causes a voltage drop; totally normal if within reason.

There is a potential reason for shunting the main, if the thing you are most worried about is a phase reversal, because that can potentially cause a lot of machinery damage quickly. But if that’s the goal, then you do NOT want to have the UV tolerance set too tightly, for the reason I said above; it might be normal. Check to see what it is set for. Someone may have adjusted it not knowing the consequences.

 

[ptonsparky]

We used Symcons until the SS overload relays started to include phase loss and under voltage. They worked well but did need to replace a few over the years. Support was excellent when they were based in a neighboring State. IIRC, Litlfuse now owns it. Never hooked them to a shunt trip main breaker. Control circuits only, usually on the largest motor. Ag work generally.