PAT Tester Accuracy

[Lorna]

Hello

I’m trying to understand the accuracy of a PAT tester which states the resolution, % and digit tolerances of individual test types.

My calculations are below for a hypothetical test and I would be very grateful if anyone could tell me if I’m doing right.


Resolution = 0.01 (2dp)
Accuracy = ±5% ±2 digits

Test Reading = 15.50

Step 1:
Determine the % tolerance
15.50 * 0.05 = 0.775

Step 2:
Round to 2dp = 0.78

Step 3:
Add the digit accuracy to least significant figure

= 0.78 + 0.02
=0.8

Therefore for a reading of 15.50

± 0.8 (5.16% of 15.50)

Upper limit = 16.30
Lower limit = 14.70

Thanks for your time

Lorna

 

[oldtimer]

I try not to study this too much as far as I am concerned as long as it as a calibration certificate stating the tester is within tolerance in other words I dont need to know how a car engine works to drive is so my question is why do you need this information ?

 

[Silly Sausage]

That looks good to me.

 

[Lorna]

Thanks I appreciate you getting back to me.

 

[SirKit Breaker]

If you look in the 3rd Edition Code of Practice for In service Inspection and Testing of Electrical equipment, there are a few pages dedicated to Test Equipment. There is all the info you will need about what you ask.

Cheers..............Howard