[Milsurplus] PP-4763 and dynamotors

[Meir Ben-Dror WF2U]

Hi Robert,

Which 28 V dynamotor are you attempting to start with the PP-4763?

73, Meir 

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On Feb 13, 2021, 1:15 PM, at 1:15 PM, Robert Goff <robert.h.goff at gmail.com> wrote:
>People smarter than me (just about all of you!):
>
>Anyone who owns one of these power supplies (built for the GRC-106)
>know that they do not handle inrush current well at all. Anything over
>50A and the breaker trips. So, in an attempt to free up my big PP-1104
>for 12 volt use, I built a "dynamotor starter" based on an ER article
>a few years ago.
>
>In the article they use 12 350F "super caps" across the power supply
>with a large power resistor (1 ohm 250 or so watts) to limit the
>inrush current.  A switch across the resistor is then used to short it
>out when the caps are charged.
>
>Since I didn't have a similar power resistor, my breadboard version
>uses a 300W light bulb as a current limiter. It takes something like 5
>minutes before the caps charge to the point that the lamp goes out, at
>which point I short the bulb and BOOM the power supply still shuts
>down.
>
>I'm thinking the super caps are not reaching full charge and obviously
>5 plus minutes is way too long to wait, but before I go and order an
>expensive power resistor, I'm wondering will a lower series resistance
>solve the problem? A 300W bulb at 120 works out to 48 ohms hot, cold
>resistance measures 3.8 ohms.
>
>Or is the PP-4763 just unsuitable for this application?  Anybody tried
>something like this? I would welcome any input or suggestions.
>
>Thanks,
>de Robert W7MKA
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