Fluke 1738 User Manual page 78

1736/1738
Users Manual
2
 
1 PF –
Formula 1:
 
0.5 + ------------------------ - % +0.005 %
3 × PF
 
2
 
1 PF –
Formula 2:
 1.2 + ------------------------ -  % +0.005 %
2 × PF
 
2
 
1 PF –
Formula 3:
 1.2 + ------------------------ -  % +0.0075 %
×
2 PF
 
2
 
1 PF –
Formula 4:
 1.7 + ------------------------ -  % +0.0075 %
×
2 PF
 
2
 
1 PF
–
Formula 5:
× ------------------------ -
 1.2 + 1.7  % +0.005 %
PF
 
Example:
Measurement at 120 V/16 A using an iFlex1500-12 in low range. Power Factor is 0.8
σ
Active power uncertainty :
P
σ
2
  
1 0.8 – ×
= ±   1.2 % + ------------------------ -  + 0.005 %
P
×
  
2 0.8
×
The uncertainty in W is
± ( 1.575 %
σ
Apparent power uncertainty
σ
± ( × )
= 1.2 % + 0.005 % S =
S
Range
×
The uncertainty in VA is
± ( 1.2 %
Reactive/non-active power uncertainty
σ
× ×
Q = ± ( 2.5 % S ) = ± ( 2.5 % 120 V
In case of a measured voltage that is >250 V, the additional error is calculated with:
×
Adder = 0.015 % S High Range = 0.015 %
72

×
P Range  = ± ( 1.575 % + 0.005 % 1000 V

× ×
120 V 16 A 0.8 + 7.5 W ) = ± 31.7 W
:
S
± ( × × ) ± (
1.2 % + 0.005 % 1000 V 150 A =
×
120 V 16 A + 7.5VA ) = ± 30.54 VA
σ
:
Q
×
16 A ) = ± 48 var
× ×
1000 V 1500 A = 225 W/VA/var
×
150 A ) = ± ( 1.575 % + 7.5 W )
)
1.2 % + 7.5 VA