Hioki PW3336-01, Instruction Manual

Page: 34 / 206

2.2 Connecting the Measurement Lines
28
Please read "Handling the Cables" (p.6) carefully before installing, connecting the
instrument, or connecting the measurement LINES.
If the object under measurement’s voltage and current levels exceed the instru-
ment’s measurement range
You can then read primary-side input values directly by setting the VT ratio and CT ratio on the instrument.
See:
"3.2.9 Setting the VT and CT Ratio"(p.59)
2.2 Connecting the Measurement Lines
Verify that power to the measurement lines has been cut off before connecting the
instrument to them.
To ensure accurate measurement
• When measuring power, the polarity of the voltage and current affects readings, so it is essential to con-
nect the instrument to the measurement lines properly. Accurate measurement will not be possible if these
connections are not made properly.
• Keep power supply wiring away from the instrument so that it is not affected by external magnetic fields.
• To prevent electrical shock and personnel injury, do not touch any input terminals
on the VT (PT), CT or the instrument when they are in operation.
• When using an external VT (PT): Do not short the secondary side.
Applying a voltage to the primary side while the secondary side is shorted will cause
a large current to flow to the secondary side, causing it to burn up and resulting in a
fire.
• When using an external CT: Do not leave the secondary side open.
Allowing a current to flow to the primary side while the secondary side is open will
cause a high voltage to occur on the secondary side, which is extremely dangerous.
e.g.) 1P2W
Corresponding with Method 1 (1)
Corresponding with Method 2 (1)
• Phase differences between an
external VT (PT) and CT can intro-
duce a large error component into
power measurements.
To ensure accurate power mea-
surement, use a VT (PT) and CT
with a small phase error in the fre-
quency band of the circuit being
used.
• To ensure safe operation, always
ground the secondary side of the
VT (PT) and CT (see figure below)