§ 12-4 Use of the wattmeter
W?
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?I
?
?
?
V N
If a positive current is flowing into the (+) end of
the current coil while the (+) terminal of the voltage
coil is positive with respect to the unmarked end,an
upscale reading is obtained.
)c os (|||| ?? ?? ??
IV
IVP ??
??
???
????
???
???
???
100)(510
100)(510
1
11
IIjI
jIIjI
AI ?4.15318.11 ???
)(1 0 0 04.1 5 3c o s18.111 0 0)4.1 5 30c o s (2 d o w n s c a l eWIVP ??????? ??
[Reverse a coil(the voltage coil)]
1I? V0100V 2 ????V901 0 0V 1
????
?
?
10 10
5j
?I
?
?
W?
?
?I
W?
?
?I
?
?
?
V N
If a positive current is flowing into the (+) end of
the current coil while the (+) terminal of the voltage
coil is positive with respect to the unmarked end,an
upscale reading is obtained.
)c os (|||| ?? ?? ??
IV
IVP ??
??
???
????
???
???
???
100)(510
100)(510
1
11
IIjI
jIIjI
AI ?4.15318.11 ???
)(1 0 0 04.1 5 3c o s18.111 0 0)4.1 5 30c o s (2 d o w n s c a l eWIVP ??????? ??
[Reverse a coil(the voltage coil)]
1I? V0100V 2 ????V901 0 0V 1
????
?
?
10 10
5j
?I
?
?
W?
?
?I