Motor Protection Relay Question

[jucesanc]

Let's say that I am replacing my current motor protection relay (GE Lodtrak III) with a GE Multilin 369. I'm hearing from a senior engineer that we need the lodtrak settings so that we can program the multilin. Problem is, from previous test reports I'm seeing that the display has failed on the lodtrak and the settings do not display. I also don't have the motor's thermal damage curve...

Will it be impossible to replace the motor protection relay without the settings on the current one? And if not, what should be my replacement strategy?

What I have are single lines, 3-line diagrams, wiring diagram for the lodtrak, pictures of the interior, manufacturer and model numbers.

 

[Jraef]

It would be best if you knew the settings used in the Lodtrak for sure. Someone decided on those settings and those decisions may have been based on information about the application that are unknown to you now. If that someone is not around any more and there were no other records kept, without the display you are SOL.

A halfway decent EE or electrician with motor protection experience should still be able to set up a 369 however, I mean what if you were NOT replacing an older model? Someone still has to set it up, right?

That said, in the 1980s when they sold them, the old GE Lodtrak unit was a fairly sophisticated relay, but is nowhere near as smart as a 369, so I highly doubt there will be anything that difficult to discover. It only protected for overload, over temperature (only IF it had an RTD module attached), phase reversal,, phase loss, phase unbalance and arcing ground fault. You can get most of this is a simple Solid State Overload Relay now...

If your EE can't deal with those basic settings, he should go look for a job... but it's more likely he just knows nothing about a Lodtrak so he wants to be extra cautious in replacing it and that's understandable. If you still have the manual, you will see (and can show him) it wasn't that sophisticated of a relay, so programming it wasn't rocket surgery. If you don't have the manual, you can download a copy here (it has an advertising watermark splashed across it, but hey, someone had to take time to scan it in, so give them that).

 

[jucesanc]

It would be best if you knew the settings used in the Lodtrak for sure. Someone decided on those settings and those decisions may have been based on information about the application that are unknown to you now. If that someone is not around any more and there were no other records kept, without the display you are SOL.

A halfway decent EE or electrician with motor protection experience should still be able to set up a 369 however, I mean what if you were NOT replacing an older model? Someone still has to set it up, right?

That said, in the 1980s when they sold them, the old GE Lodtrak unit was a fairly sophisticated relay, but is nowhere near as smart as a 369, so I highly doubt there will be anything that difficult to discover. It only protected for overload, over temperature (only IF it had an RTD module attached), phase reversal,, phase loss, phase unbalance and arcing ground fault. You can get most of this is a simple Solid State Overload Relay now...

If your EE can't deal with those basic settings, he should go look for a job... but it's more likely he just knows nothing about a Lodtrak so he wants to be extra cautious in replacing it and that's understandable. If you still have the manual, you will see (and can show him) it wasn't that sophisticated of a relay, so programming it wasn't rocket surgery. If you don't have the manual, you can download a copy here (it has an advertising watermark splashed across it, but hey, someone had to take time to scan it in, so give them that).

Not sure if this is going to show up big enough to read.. but I found an older test, that shows values before the display failed. Just not sure how to decipher the results.