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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => AC Power and Grounding => Topic started by: Mike Sokol on February 26, 2018, 09:08:27 pm

Title: New Load Bank
Post by: Mike Sokol on February 26, 2018, 09:08:27 pm
Well, it's not 5 Megawatts, but it's a 10kW 120/240-volt load bank with 1kW increments that's perfect for my demonstrations. I just bought in on eBay a few days ago and it should arrive around the end of week. Let the loading begin...
Title: Re: New Load Bank
Post by: Jonathan Johnson on February 27, 2018, 06:07:15 pm
And you can use it to heat your workshop!
Title: Re: New Load Bank
Post by: Mike Sokol on February 27, 2018, 06:49:16 pm
And you can use it to heat your workshop!

While monitoring the voltage and current!  ;D
Title: Re: New Load Bank
Post by: Mike Sokol on March 01, 2018, 01:40:07 pm
My 10kW Load Bank just arrived, and I had a take a selfie with it since my wife refused to take a picture of me with some "ugly gear". I think Linda's jealous.
Title: Re: New Load Bank
Post by: TJ (Tom) Cornish on March 01, 2018, 04:32:23 pm
My 10kW Load Bank just arrived, and I had a take a selfie with it since my wife refused to take a picture of me with some "ugly gear". I think Linda's jealous.
Very nice!
Title: Re: New Load Bank
Post by: brian maddox on March 01, 2018, 09:36:54 pm
Quote
  Well, it's not 5 Megawatts, but it's a 10kW 120/240-volt load bank with 1kW increments that's perfect for my demonstrations. I just bought in on eBay a few days ago and it should arrive around the end of week. Let the loading begin...


Wait, isn't this just futile?  That's what the borg always said....
Title: Re: New Load Bank
Post by: Mike Sokol on March 06, 2018, 02:08:39 am
Now I need a few test connectors for my load bank to tie into incoming power. I'm thinking about getting the cheapest KWh meter I can find, gut out the electronics, and bolt a pair of lugs on the bus bars so I can hang a few pieces of #2 gauge wire out of the side. Any thoughts?
Title: Re: New Load Bank
Post by: Tim McCulloch on March 06, 2018, 03:18:09 am
Now I need a few test connectors for my load bank to tie into incoming power. I'm thinking about getting the cheapest KWh meter I can find, gut out the electronics, and bolt a pair of lugs on the bus bars so I can hang a few pieces of #2 gauge wire out of the side. Any thoughts?

Uh... you're not looking for a UL label, right?
Title: Re: New Load Bank
Post by: Mike Sokol on March 06, 2018, 06:48:18 am
Uh... you're not looking for a UL label, right?

Hell no!!!  ;D

In all seriousness this is for professional use only. So I need to make this test procedure as safe and professional as possible. That's why I'm NOT going to use car jumper cables to clamp onto the hot lugs in the meter box.  :o
Title: Re: New Load Bank
Post by: Chris Hindle on March 06, 2018, 12:28:04 pm
Hell no!!!  ;D
In all seriousness this is for professional use only. So I need to make this test procedure as safe and professional as possible. That's why I'm NOT going to use car jumper cables to clamp onto the hot lugs in the meter box.  :o
Don't forget to let the mic squeal when you walk up to it.....
Chris.
Title: Re: New Load Bank
Post by: Mike Sokol on March 06, 2018, 05:23:39 pm
Don't forget to let the mic squeal when you walk up to it.....
Chris.

So they know the mic is ON, right?  :o
Title: Re: New Load Bank
Post by: Jonathan Johnson on March 06, 2018, 06:30:30 pm
So they know the mic is ON, right?  :o

I believe the exact quote is:

<SQUEEEEEEL> <tap> <tap> "Is this thing on?"

(As if the squeal wasn't sufficient to let them know that it is.)

But you and I both know that if a microphone has a switch, the talent will turn it off when they leave the stage. And the next "talent" will exhibit the complete inability to understand that the mic is off, let alone find the switch.
Title: Re: New Load Bank
Post by: Dennis Wiggins on March 06, 2018, 07:37:23 pm
Well, it's not 5 Megawatts, but it's a 10kW 120/240-volt load bank...

Does this present a purely resistive (not in this dictionary) load?  Just curious.

-Dennis
Title: Re: New Load Bank
Post by: Mike Sokol on March 06, 2018, 11:11:20 pm
Does this present a purely resistive (not in this dictionary) load?  Just curious.

-Dennis

Yes, they call it a "Resistive" Load Bank, and there's not an inductor or capacitor in sight. http://www.steadypower.com/products.php?product=Avtron-K490-Portable-Load-Bank-%2810kW%29
Title: Re: New Load Bank
Post by: Mike Sokol on March 07, 2018, 12:08:28 pm
I only had one problem with my new load bank, the panel amp meter was dead. I used a greenie screwdriver to adjust the zero position, just in case the meter movement was stuck. But that didn't do anything. I opened up the case and measured across the amp meter itself (after disconnecting the leads) and it read around 0.1 ohms as expected. I did the same on the current transformer and it also read around 0.1 ohms as expected. It did appear that one of the leads connecting the current transformer to the meter was open, but it disappeared into a wiring harness bundle and couldn't be physically traced without cutting apart a beautiful wiring job. Ugh.

I didn't have a user's manual or schematic in hand because they're not on the interweb, and the manufacturer hadn't sent me one yet. But this morning I received an email with both the user manual AND the schematic. A quick look at the schematic for 10 seconds showed me what was wrong and the solution. There's a pair of 5-way binding posts on the front panel so you can use an external amp meter, and it's in series with the current transformer and meter. So you need to install a shorting jumper (yes, with its own long part number) if you want to use the on-board panel meter. Of course there was no shorting jumper supplied with the used unit. Also, there was no schematic or user manual either, which clearly states you need a shorting jumper to use the panel amp meter. So a short jumper wire solved the problem and all is now right with the world.

I'm getting ready to go into action with this thing in a few weeks and will remember to make the microphone "squeal". Thanks for reminding me of this hallowed tradition.  :o
Title: Re: New Load Bank
Post by: Mike Sokol on March 14, 2018, 03:23:19 pm
Uh... you're not looking for a UL label, right?

Here's what I bought new for $32.50 including shipping... I'll cut a hole in the Lexan cover and hang a few #2 gauge wires out of it that can feed the load bank. I'll need to split off separate ground and neutral wires that can attach directly to the service panel bus bars, but looks like this should do the trick. I also get a bonus current transformer I don't need, but I'm sure there will be a future experiment. 

Title: Re: New Load Bank
Post by: Tim McCulloch on March 14, 2018, 04:54:29 pm
Here's what I bought new for $32.50 including shipping... I'll cut a hole in the Lexan cover and hang a few #2 gauge wires out of it that can feed the load bank. I'll need to split off separate ground and neutral wires that can attach directly to the service panel bus bars, but looks like this should do the trick. I also get a bonus current transformer I don't need, but I'm sure there will be a future experiment.

So this is for a demo rig for a special project?  What scenarios are you presenting?
Title: Re: New Load Bank
Post by: Mike Sokol on March 14, 2018, 06:24:22 pm
So this is for a demo rig for a special project?  What scenarios are you presenting?

I can't talk specifics just yet, but at some point I'll be able to share details with you. Lots of measuring to do.
Title: Re: New Load Bank
Post by: Tim McCulloch on March 14, 2018, 06:41:36 pm
I can't talk specifics just yet, but at some point I'll be able to share details with you. Lots of measuring to do.

Uh huh... I see what you did there and I have a pretty good idea what's up.  I'll be patient.
Title: Re: New Load Bank
Post by: Mike Sokol on March 15, 2018, 07:21:51 am
Uh huh... I see what you did there and I have a pretty good idea what's up.  I'll be patient.

Thanks.... You will be the last one to go.
Title: Re: New Load Bank
Post by: Tim McCulloch on March 15, 2018, 12:35:31 pm
Thanks.... You will be the last one to go.

"It's a cook book!"
Title: Re: New Load Bank
Post by: brian maddox on March 15, 2018, 07:20:15 pm
 
"It's a cook book!"

 ;D
Title: Re: New Load Bank
Post by: Mike Sokol on March 15, 2018, 08:38:23 pm
"It's a cook book!"

Exactly....
Title: Re: New Load Bank
Post by: Mike Sokol on April 25, 2018, 09:34:23 pm
Used my load bank in battle today and ran a really interesting test where I reversed the neutral and ground lines to test the EGCís ability to sink 45 amps of fault current. And I was able to find that it opened up after 1 minute of heating, but then slowly returned to continuity once it cooled down in 5 minutes. You canít get those kinds of results from an impulse test. You need steady state current.
Title: Re: New Load Bank
Post by: Ron Hebbard on April 26, 2018, 04:01:50 am
Used my load bank in battle today and ran a really interesting test where I reversed the neutral and ground lines to test the EGCís ability to sink 45 amps of fault current. And I was able to find that it opened up after 1 minute of heating, but then slowly returned to continuity once it cooled down in 5 minutes. You canít get those kinds of results from an impulse test. You need steady state current.
4 Queries:  What gauge and material was the EGC?
How and where did it fuse or open?
What gauge was it at its narrowest point after it had cooled and regained conduction? 
Where would it fuse, and at what current, on a subsequent test?
Toodleoo!
Ron Hebbard.
Title: Re: New Load Bank
Post by: Mike Sokol on April 26, 2018, 09:33:12 pm
4 Queries:  What gauge and material was the EGC?
How and where did it fuse or open?
What gauge was it at its narrowest point after it had cooled and regained conduction? 
Where would it fuse, and at what current, on a subsequent test?
Toodleoo!
Ron Hebbard.

I can't go into a lot of detail just yet, but this was an 8-gauge copper wire that was wire nutted onto a 12-gauge copper wire, and was then terminated in a standard bus bar in a service panel. I'll fill you all in on more details once I'm allowed, but this was interesting because an Ideal SureTest Analyzer showed the EGC impedance as perfect at around 0.5 ohms, but my Load-Bank test revealed a completely different failure mode I didn't predict. And there were several others witnessing it, so it's fully documented.
Title: Re: New Load Bank
Post by: Jonathan Johnson on April 27, 2018, 01:56:37 am
I can't go into a lot of detail due to a pending litigation, but this was an 8-gauge copper wire that was wire nutted onto a 12-gauge copper wire that was buried underground, and was then terminated in a standard bus bar in a service panel.
I'll fill you all in on more details once I'm allowed, but this was interesting because an Ideal SureTest Analyzer showed the EGC impedance as perfect, but my Load-Bank test revealed a completely different failure mode I didn't predict. And there were several other EE's witnessing it, so it's fully documented.

Speculating here... it sounds like a case of an unforeseen problem in a design, and you were called to figure out what happened (kind of a failure analysis thing). Since there is "pending litigation" then maybe one party is trying to prove that the other party was negligent -- that "they should have known" this could happen. But maybe it couldn't have been predicted because the exact scenario involved failure modes that didn't fit the existing models.

That's just a guess. Maybe I'm out-of-turn here.
Title: Re: New Load Bank
Post by: Mike Sokol on April 27, 2018, 04:59:56 am
Speculating here... it sounds like a case of an unforeseen problem in a design, and you were called to figure out what happened (kind of a failure analysis thing). Since there is "pending litigation" then maybe one party is trying to prove that the other party was negligent -- that "they should have known" this could happen. But maybe it couldn't have been predicted because the exact scenario involved failure modes that didn't fit the existing models.

That's just a guess. Maybe I'm out-of-turn here.
I canít say any more right now. Maybe in 6 months. But Iíll draw up a hypothetical test situation next week. What I did was really simple but very easy to explain once you see it.