HP Extech 380976 - Manual (Page 9)

380976 V3.2 4/11 9
NOTE
Once a phase is selected as COM, users can not change this selection in the
subsequent measurement. For example, if S (or L2) phase is selected, S (or L2)
phase is always connected to the COM during measurement of W
RS
(or W
L1L2
) and
W
TS (or W L3L2
) in 3φ 3W unbalanced power.
NOTE
1. The "+" sign printed on Panel must face the power source for accurate
measurement.
2. If the device under test is a switching power supply, the meter KW, PF and θ
reading maybe incorrect.
NOTE
For 3φ3W unbalanced power measurements, WRS or WTS could be negative.
Ensure that all connections are correct before accepting a reading as valid.