good info.  thanks!

On Nov 28, 2013, at 4:56 PM, John Cooper wrote:

Today I inserted a 75A / 50mV shunt in the power lead to my hydraulic pump in order to measure the current draw. I connected my Fluke 87-V digital voltmeter on the 600mV range across the sense terminals of the shunt . With the pump running in the "gear down" direction and the equalization valve open, the motor was drawing a steady 29 Amps. I then shut off the pump, closed the equalization valve, and with the Fluke in the "250 uS peak" mode, measured the inrush when the pump started up again briefly. Would you believe 135 Amps!  (Disclaimer: I purchased the shunt on eBay and can't vouch for its calibration.)

Next time the plane is up on jacks, I'll re-do this test in both gear up and gear down directions. Also, I intend to temporarily remove the ZNRs across the hydraulic relay contacts and measure the voltage spikes with no protection.


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