1

Let's say you have a device that is rated at the following:

  • 550 amps @ 12Vdc (heat)
  • Max Voltage = 48Vdc (insulation material max voltage rating)

I am mainly concerned with the heat, we could say the device is able to handle: 550A x 12V = 6,600 Watts

So if you use the same power to determine how much current it can handle at 24Volts, would the statements below be true?

Current x 24V = 6,600 Watts Current = 275A

275Amps @ 24Vdc?

Current x 48V = 6,600 Watts Current = 137.5A

137.5Amps @ 48Vdc?

enter image description here

Busta
  • 35
  • 7
  • What the limit is (voltage? Power? Current handling?) will be defined in the datasheet and can especially not be extrapolated from the data you give us without knowing what kind of device we're talking about – most devices specified for 12 V will simply break when supplied with 24 V . – Marcus Müller Mar 16 '19 at 12:53
  • @MarcusMüller 12V starters work fine on 24V - not permanently though, but a useful way to get an old crawler to start... The engine sounds like it is about to leap out... BUT make sure **all** the other electrics are disconnected... – Solar Mike Mar 16 '19 at 12:56
  • @SolarMike I might be confused here, but where does it say "starter"? – Marcus Müller Mar 16 '19 at 12:56
  • A starter is a 12V device... unless your definition of device is different... – Solar Mike Mar 16 '19 at 12:57
  • ahhh, as counterargument to the "most devices will simply break"; true, but then again, this doesn't seem to be just any motor or resistive element – somehow, OP can control the current through it even when they double the supply voltage. – Marcus Müller Mar 16 '19 at 12:58
  • @MarcusMüller so what devices take 550A at 12V as per the OP question? easiest one I can think of is a starter motor... – Solar Mike Mar 16 '19 at 12:59
  • @SolarMike good point! – Marcus Müller Mar 16 '19 at 12:59
  • @SolarMike hm, maybe the combined heater supply of a Wullenweber CDAA vacuum tube receiver array? A coil gun? A copper production electrolytic bath? I'm opting for these more interesting variants, to be honest! – Marcus Müller Mar 16 '19 at 13:01
  • Hmmm it should maiybe also be mentioned that just because a "device" is rated for 550A and 12V doesn't mean the device is dissipating that full amount. From the way the question is phrased, I can't tell if "(heat)" means the device is a heater or that OP is certain that the device converts all of that energy to heat. I guess really I'm just agreeing that it would be nice to know what the device is. – K H Mar 17 '19 at 05:10
  • hehe, sorry everyone. Was away from my computer all day. This is a simple pass-thru stud with insulating material designed to pass through power through a panel. The documentation stated what the max voltage allowed, which is 48Vdc, but they only listed 12Vdc @ 550amps. I am sending 24Volts through this device so I figured the current rating is now 275Amps. – Busta Mar 17 '19 at 12:12
  • By the way, I am not trying to control the current or limit it, I am simply trying to find out the current rating of this device after I increase the voltage to 24Vdc. – Busta Mar 17 '19 at 12:18

2 Answers2

0

Double the voltage, halve the current for the same power.

As you hold the power constant then your example is true.

Just as expected, that's why high power systems tend to have high voltage instead of high current as insulation is cheaper than metal conductor...

Solar Mike
  • 6,319
  • 1
  • 12
  • 28
  • If you have the same resistance and you double the voltage, you also double the current... – Hearth Mar 16 '19 at 13:43
  • @Hearth Thanks... – Solar Mike Mar 16 '19 at 13:46
  • I was wondering if this held true for ratings as well, like the simple pass-thru stud I am discussing now. I am assuming they are worried about two things: Heat and Material (how high of a voltage can it contain) – Busta Mar 17 '19 at 12:14
0

This question cannot be answered without more information about your "device". If the device is a simple resistive element, perhaps a resistance heater, then doubling the voltage will double the current and quadruple the power consumed.

On the other hand, your device may operate from a dc/dc converter. In this case the power consumption would be relatively constant over the range of input voltages, and the current would decrease as the voltage increased.

Elliot Alderson
  • 31,192
  • 5
  • 29
  • 67
  • My device is a simple pass-thru stud designed to pass a power source through a panel. It has two studs, a copper core, and insulating material around the copper core. Hence the max voltage rating of 48Vdc. – Busta Mar 17 '19 at 12:13