Hioki PW3337-01 - Chapter 3 Configuration and Measurement; 3.1 Pre-Measurement Inspection

2.2 Connecting the Measurement Lines
33
Selecting the connection method (Example: 1P2W connection)
Depending on the input level, the power meter’s instrument loss may affect measured values. Select the con-
nection method below with the lower loss.
Example:
When measuring 12 V, 65 A
Method 1: Loss = (12 [V])
2
/ 2 [MΩ] = 0.000072 [W]
Method 2: Loss = (65 [A])
2
× 1 [mΩ] = 4.225 [W]
Method 1 is characterized by lower loss and therefore allows more accurate measurement.
When measuring 1,000 V, 10 mA
Method 1: Loss = (1,000 [V])
2
/ 2 [MΩ] = 0.5 [W]
Method 2: Loss = (10 [mA])
2
× 1 [mΩ] = 0.0000001 [W]
Method 2 is characterized by lower loss and therefore allows more accurate measurement.
Method 1
Connect the voltage input terminals to the
load side.
Method 2
Connect the current input terminal to the
load side.
Loss = (Input voltage [V])
2
÷ 2 [MΩ]
Loss = (Input current [A])
2
x 1 [mΩ]
Power measurement includes loss from the
voltage input terminals’ input resistance.
Power measurement includes loss from the cur-
rent input terminals’ input resistance.
Power
supply
Load
Current input resistance
Voltage input resistance
Load
Power
supply
Current input resistance
Voltage input resis-
tance
1 mΩ 1 mΩ
2 MΩ
2 MΩ
Power
supply
Load
Current input resistance
Voltage input resis-
tance
Load
Power
supply
Current input resistance
Voltage input resis-
tance
1 mΩ 1 mΩ
2 MΩ2 MΩ
U
L
N
±
±
I
±U
±
I
L
N
U
U
±
±
±
I
±
I
±
LL
NN