Eutectic Alloy vs E100 Solid State Overload

[CuriousElectron]

Hello All,
What are uses and pros/cons of Alloy type O/L versus Solid state O/L for a single speed motor in the range of 20 HP? Does it depend on environment where a motor is installed? Cost?
Any thoughts on where you'd use either one would be appreciated. My understanding is that both types are user resettable.
Thanks!
EE

 

[mparenteau]

Solid state OLs will give you some flexibility on setting based on FLA. Some have phase loss settings for motor protection as well.

Mike

 

[waross]

My experience with Eutectic Alloy overloads is very good.
One drawback is the lack of adjustment with Eutectic Alloy overloads.
You must change the heater element to change the settings.
I was responsible for dozens of motors and I had a full selection of all sizes on hand.
With only a few motors, changing settings may mean a trip to the distributor.
That said, my application was in a sawmill at a time when designers typically undersized sawmill motors.
That was in the last days of the U-frame motors and a U-frame motor would run continuously under overload conditions that would quickly fry a T-frame motor.
It was common to go one or two sizes larger on the O/L heaters than was recommended.
If your motor has no special loading characteristics, you should be able to use the recommended heaters and never have to change.
One caveat: Beware of operator error with Eutectic Alloy overloads.
After a trip, and with our undersized motors trips were frequent, an impatient operator would repeatedly try to reset a hot O/L.
This would result in the alloy not setting up homogeneously.
The O/L would then trip at much less than rated current and the heater would have to be have to be replaced.
Heater: The replaceable link that includes the Eutectic Alloy element.

 

[LionelHutz]

Eutectic alloy overloads are rather old school these days. I wouldn't use one these days, haven't touched one in 20 years now.

Electronic ones are probably as cheap and will provide better protection with most having more protection that just the thermal overload function.

The A-B E100 overload seems like it'd be a much better choice than the eutectic alloy overload.