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Can't get PA1000 low current measurement

PA1000, PA3000, PA4000
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BobM3
Posts: 2
Joined: December 16th, 2015, 9:58 am

Can't get PA1000 low current measurement

Post by BobM3 » December 16th, 2015, 10:08 am

I bought the PA1000 along with the CL200 current clamp (1 ma/amp output). I'm trying to measure motor current. It should be about 6.5 amps RMS. The meter reads 0. I've used both the 20 amp input and the 1 amp input. I've scaled the reading to 1000.0. I selected the proper shunt input. I do get a reading that is correct when I don't use the probe and just wire the meter in series with the motor.

I checked the current probe using a scope and a 1 ohm shunt resistor. It reads about as expected - 5.5 Volts RMS (the resistor is a 10%er).

When the motor starts up I do get a non-zero reading for the first fraction of a second. I assume it's because the motor is pulling about 80 amps on startup.

Any suggestions as to what the problem might be?

David N
Tektronix Applications
Tektronix Applications
Posts: 558
Joined: July 31st, 2008, 8:26 am

Re: Can't get PA1000 low current measurement

Post by David N » December 18th, 2015, 8:32 am

In the PA1000, "Blanking" is normally enabled. With blanking enabled, the analyzer will return a zero when the measured signal is less than a certain percentage of the bottom range. Try selecting Disable when measuring voltage or current that are small. Refer to page 22 of the user manual 077-0912-01.

BobM3
Posts: 2
Joined: December 16th, 2015, 9:58 am

Re: Can't get PA1000 low current measurement

Post by BobM3 » December 29th, 2015, 1:25 pm

Thanks Hiker - that did the trick! I'm very happy with the meter so far.

Bob M

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