Braking resistor used as a load bank

loosegravel

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Braking resistor.jpg
I've been buying and selling the MEP generators for a couple of years now. When I "show" one to a perspective buyer I usually connect it to my shop main panel where I can turn on various different breakers to show that it's producing power. I've been looking for a load bank for a while now, and also kicking around the idea of building one. I bid on a couple of "braking resistors" that I saw on Iron Planet yesterday. Not knowing what they really were, I took a chance. Well of course I won them both. They're brand new "Gino ESE" braking resistors. The identification plates have them at 1.5 ohms, 1100 volts and 1400 amps. Of course that's way to "hot" for load testing these marvelous MEP generators. But using ohms law if I supply 208vac across something that's 1.5 ohms that comes out to a little over 138 amps or 28.5kw. That's still a little to hot for the smaller generators. But I'm wondering if I could reconfigure something like this to have individual, smaller loads and use 20 amp toggle switches to apply them? Also, there is a bolt on one end of the box that sandwiches all of these plates together. It looks like it could also be used like a "carbon pile" DC load tester, only it would be A/C instead. I'm just wondering if anyone here has any experience with using a braking resistor as a load bank. Maybe I have essentially purchased a couple of $200 boat anchors! Ahh yes, it wouldn't be the first time!
 

joeblack5

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It looks like these are cast iron resistors. They are designed for short duration.

Are these modules in series or in parallel?

Maybe getting the plate heaters from a cold weather heatpump or better industrial electric heater might be a better way to go.

Are you testing in single or three phase?

Good luck
Johan
 

loosegravel

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It looks like these are cast iron resistors. They are designed for short duration.

Are these modules in series or in parallel?

Maybe getting the plate heaters from a cold weather heatpump or better industrial electric heater might be a better way to go.

Are you testing in single or three phase?

Good luck
Johan
Thanks Johan. Yes, these are cast iron plates in series. I'm thinking that with some air flow across these plates they could sustain a load for a much longer time. I was using 120 volts single phase with one unit only and pulling from 60 - 80 amps. The amperage draw seemed to increase as the plates heated up. Using ohms law with 1.5 ohms and 240 volts that would be 160 amps. Too much for the generators that I'm working with. One thing that I haven't tried is 240 volts with the two of them in series. That would be 240 divided by 3.0 ohms = 80 amps. That's still a little too much for the 10kw units, but the larger generators may be able to handle that load. At any rate, I think that these braking resistors belong in the hands of someone who is suddenly slowing down a motor of some sort. Like you said...with no air flow short duration loads are what they're designed for. Thanks for your input!
Jeff
 

papakb

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A load bank that's larger than you need isn't a problem but one thats smaller than you need will eventually burn out. A cooling fan will certainly help but I'd suggest ducting it outside of the shop. The load is typically only used for short periods to make sure the regulator is capable of regulating the output when it's under full load.

Unlike the RF load banks used with radios that need to terminate the output power from a transmitter to waveguides and antenna feeds when you don't want any emmissions, power banks are just used to test the regulators to make sure they're capable of meeting their specifications.
 

loosegravel

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Enumclaw, Washington
A load bank that's larger than you need isn't a problem but one thats smaller than you need will eventually burn out. A cooling fan will certainly help but I'd suggest ducting it outside of the shop. The load is typically only used for short periods to make sure the regulator is capable of regulating the output when it's under full load.

Unlike the RF load banks used with radios that need to terminate the output power from a transmitter to waveguides and antenna feeds when you don't want any emmissions, power banks are just used to test the regulators to make sure they're capable of meeting their specifications.
Yes sir, thank you for your input. I was referring to an over-load occurrence on the generator from using a low resistance load. Low resistance equals high current. These gen sets can be loaded up to 125% of their rated load and they will run...for a short time before faulting for over-current. While using one of these braking resistors to put a load on the 10kw generator it was in fact drawing 80 amps on 120 volts. The generator handled it for a short time before faulting for over-current. I would need to add more cast iron plates into the equation to increase the resistance which would decrease the load. Many of us just need to get back to basics and use ohm's law. It works! Thanks again.
 
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