# Overall accuracy method

Discussion in 'Electronics Resources' started by Benengineer, May 24, 2016.

1. ### Benengineer Thread Starter Member

Feb 6, 2016
133
2
Is there anyone helping me with overall accuracy power measurement? Here is the case. Based on the Power analyzer specification, I figured out what voltage error and current error were, which are accuracy. However, my boss asked me to figure out overall accuracy is. I asked him what overall accuracy is. He can't really explain it to me. Can you guys help me to figure out what overall accuracy is?

Specification of products:
Current Meter reading ±( 0.05%reading + 0.1%range + 1digit):
Power Meter reading ±( 0.04%reading + 0.04%range + 1digit):
Voltage Meter reading based on ±( 0.05%reading + 0.1%range + 1digit):
Input Range (RMS)
Voltage CF=3: 15/30/60/150/300/600V
Current CF=3:0.5/1/2/5/10/20A

Voltage Meter reading based on ±( 0.05%reading + 0.1%range + 1digit):
When Input voltage is 277V, the error range equals to 276.561V to 277.44 (277±277*0.05%+300*0.1%+0.001)
Number Name Reading Range 1 digit Low High Error
Voltage(V) 277 300 0.001 276.5605 277.4395 0.15866%
Current (A) 5 10 0.0001 4.9874 5.0126 0.25200%
Power (W) 1385 3000 0.0001 1383.246 1386.754 0.12665%

Thanks

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2. ### WBahn Moderator

Mar 31, 2012
23,384
7,096
Don't you just love it when someone asks you to determine the system purdumble and when you ask them what the system purdumble is, they tell you that they don't know. The obvious next question is, okay, so let's say that I determine the system purdumble and tell you what it is -- how are YOU going to then use that piece of information when YOU don't know what that piece of information even means?

My guess is that, in the situation you describe, the interest is in knowing the accuracy bounds of the overall power based on the uncertainties in the various measurements that go into calculating the overall power.

joeyd999 likes this.
3. ### Benengineer Thread Starter Member

Feb 6, 2016
133
2
I already showed the overall power accuracy in the last table.

Number Name Reading Range 1 digit Low High Error
Voltage(V) 277 300 0.001 276.5605 277.4395 0.15866%
Current (A) 5 10 0.0001 4.9874 5.0126 0.25200%
Power (W) 1385 3000 0.0001 1383.246 1386.754 0.12665%

If you have any idea, please show me.
Thanks

4. ### WBahn Moderator

Mar 31, 2012
23,384
7,096
You are using a 5-digit current meter and a 5-1/2 digit voltmeter?

You also indicate that you have a power meter. So how are you making the power measurements? With the power meter or with the voltage and current meters.

Are you meters average-responding or RMS-responding (and that does NOT mean what the value they display is supposed to be)?

Is this an AC system or a DC system? If AC, it is single-phase or three-phase? If AC, how are you measuring the phase angle between the voltage and the current?

5. ### Benengineer Thread Starter Member

Feb 6, 2016
133
2
This is not real measurement yet. But this is a calculation to verify data i got from the meter analyzer menu. This is ac input at 277V and 5A. One single phase. All my calculation above are based the specification. Please see my attachment.

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