OT Overloads

We have some AB 193-TA series electronic overloads that are dong some strange things. The motor can be running all day long pulling about 2.7 amps the overload is set to 6 amps which is the lowest setting and when you stop the motor the overload trips?

A couple guys have seen this here before on other machines but were never able to figure it out.

What would make a electeronic overload trip when you turn the motor off?

Some products in the 193 series have had problems. But it may not be your particular unit.

Not sure if this is related, but we had a PowerFlexVFD that had run fine for 3 years. Then due to "cycle time improvements" (driving harder) it started faulting.

We had to install a Load Resistor to burn off the extra power generated during braking.

Wait... are these overloads on a drive output?

No this is not on a drive this is Across the line Starting.

480 Volt 3 Phase.

bernie_carlton said:

Some products in the 193 series have had problems. But it may not be your particular unit.

Click to expand...

The recall was on the following:

e-mail said:

[FONT=&quot]Subject: E1 Plus Electronic Overload Relay Product Notice[/FONT][FONT=&quot][/FONT]
[FONT=&quot]Bulletin [/FONT][FONT=&quot]193-ED**, 193-EE**, 193S-EE**, 592-EE**, and 592S-EE** [/FONT][FONT=&quot]Series C[/FONT]

Click to expand...

The problems with those was the exact opposite. They would sometimes run overloaded and not trip.

Have you seen this?

The Plc Kid said:

We have some AB 193-TA series electronic overloads that are dong some strange things. The motor can be running all day long pulling about 2.7 amps the overload is set to 6 amps which is the lowest setting and when you stop the motor the overload trips?

A couple guys have seen this here before on other machines but were never able to figure it out.

What would make a electeronic overload trip when you turn the motor off?

Click to expand...

We had a similar issue with the 193 Electronic Overloads a few years ago. At first our local AB representative said he hadn't heard of any problems. Then as they got more of them in use, and problems started popping up at a number of sites. They ended up taking all ours back, and replacing them with a different production run. This resolved the issues we were having.

I would contact your local AB supplier and get them involved. If you don't get any help from them, I would phone AB and ask to talk to an Applications Engineer.

Stu.....

I'll repeat dmroeder's observation: The OP is describing the exact opposite problem from the 193 E1 Plus overload relay issue.

In addition, the 193-TA are bimetallic overload relays, not electronic overload relays.

While both of these devices are made by Rockwell Automation and perform the same function in motor protection, they are different in their design, construction, and operating principles.

Apples vs. Oranges.
Paper vs. Plastic.
Moose vs. Squirrel.

Ken Roach said:

I'll repeat dmroeder's observation: The OP is describing the exact opposite problem from the 193 E1 Plus overload relay issue.

In addition, the 193-TA are bimetallic overload relays, not electronic overload relays.

While both of these devices are made by Rockwell Automation and perform the same function in motor protection, they are different in their design, construction, and operating principles.

Apples vs. Oranges.
Paper vs. Plastic.
Moose vs. Squirrel.

Click to expand...

I am sorry if I have offended you in some way Ken. The OP described the 193 Overloads as Electronic. I had no reason to disbelieve him, and the AB Product line changes from time to time. We had the issues I described with 193 Electronic Overloads. I was only trying to help in resolving his issue.

Stu....

Forgive the crankiness. Some mornings the coffee's not strong enough, you know ?

So, anyone who's interested in the 193-E series E1 Plus Overloads and their trip problems, let's take that up in a different thread.

Hopefully the OP will re-post with an update: are these electronic overload relays (E1 Plus or similar) or are they really 193-TA series bimetallic relays ?

And the real point: what would cause an Overload relay to trip when an across-the-line motor starter was opened ?

My first guess is that there might be something on the machine that is increasing the load right before the contactor opens. Maybe there's a mechanical brake that closes at almost exactly the same time. Still, bimetallic overload relays aren't known for their speed.

These aren't very large, either; they are set for just 6A, the OP said, and run along at about 2.7 most of the time. So a giant jostle or physical shock of the motor contactor isn't the problem.

My suggestion for troubleshooting would be to put a clamp-on meter upstream of the contactor and set it to capture the peak current. See if the overload really is reacting to a measurably high current condition.

Hi Ken,

I just got a product service notice on 193-E series listing 50+ overloads we have purchased and thats only up till April, we have probably purchased another 50 since then!

I'll start another thread at your suggestion.

Marc

I did not know this was bimetallic overload. This one this morning is on a motor for the blower fan of a larger motor no brakes or anything that could increase the load.

I had a fluke amp clamp on peak hold on the line side of the contactor and the load side current never went above 4.2 amps.

This is very repeatable and contact resistance on the contactor is less than 1 ohm on all 3 phases.

Is this overload attached to the contactor? I wouldn't be as quick as Ken to dismiss mechanical causes.

Keith

Keith it is attached and those connections were checked also.

We have had this happen on other equipment a few times with very similar wiring and the same series overload.

I have some of the E1 and E3 overloads and have had some E1 units not trip when they should have.