Assuming you are working on an Aircraft, where the Ground Power Unit (GPU) is rated at 28V DC with max. 1000 amperes. What is the danger involved if your are to increase the current rating of the GPU to 1200 amps?

  • 2
    $\begingroup$ Are you talking about increasing the load current or the GPU current rating? $\endgroup$
    – Sanchises
    Oct 19 '18 at 6:23
  • $\begingroup$ Your question is unclear. "Increase the Amperage to 1200" could mean more than one thing. Do you mean increase the load to the external power? Increase the capacity of the external power? Or ?? $\endgroup$ Oct 19 '18 at 9:40
  • $\begingroup$ @Sanchises I meant The GPU current rating ..to increased from 1000 Amperage which is the Aircraft Amperage rating ......to 1200 Amperage which is more than the required current ,voltage remains the same. ( 28VDc ) $\endgroup$
    – Waziri
    Oct 20 '18 at 8:39
  • $\begingroup$ @JuanJimenez what I mean the Aircraft specs says the External power is 28VDC,1000 Amperage ,,, now take this scenario...someone ignorantly tempered with the GPU Amperage increase it to 1200 Amperage...now you want to power the Aircraft... assuming you were not aware the GPU Amperage was above limit....in that case what damage could possibly be ? Thank you. $\endgroup$
    – Waziri
    Oct 20 '18 at 8:48
  • 1
    $\begingroup$ No damage, as per my answer $\endgroup$
    – Dan
    Oct 20 '18 at 13:53

I find the easiest way to think about Volts and Amps is that the voltage is "pushed" and the amps are "pulled".

This is the same with pretty much any kind of power supply, whether we're talking mobile phones or planes.

To that end, the voltage requirement always needs to match. If your device is expecting 28Volts in DC then your power supply MUST provide 28Volts in DC - anything else is likely to damage it, could cause a danger and almost certainly won't work.

But current (Amps) is different - your power supply needs to meet or exceed the current demands. So if your device can pull up to 1000 Amps, the power supply MUST be able to provide 1000 Amps or more.

So, to answer your two possible questions. You can increase the Power Supply (GPU) to a 1200 Amp model (or beyond) with no ill effects, but your device (The aircraft) must have a current demand that meets or is less than that.

  • $\begingroup$ I agree. No damage from having an external power supply capable of handling more load than the aircraft can create. What the placard is saying is that any external power supply must be able to handle at least a 1k ampere load. $\endgroup$ Oct 21 '18 at 9:15
  • $\begingroup$ Hello I have another question pls $\endgroup$
    – Waziri
    Dec 20 '18 at 9:33
  • $\begingroup$ Good afternoon sir $\endgroup$
    – Waziri
    Dec 20 '18 at 9:40
  • $\begingroup$ Pls i am installing a new GTN 650 with an External CDI (HSI KP1 552 ) everything seems to be normal before connecting the GTN ,,after connecting the GTN my NAV fla g stays it doesn’t Go OFF $\endgroup$
    – Waziri
    Dec 20 '18 at 9:43
  • $\begingroup$ And if i disconnects the GTN from power My HSI behaves fine $\endgroup$
    – Waziri
    Dec 20 '18 at 9:45

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