Iwatsu SY-956, Instruction Manual

Page: 20 / 44

10
In conclusion, by substituting H
p
of formula (12) into the first term of formula (7),
(13),
the actual iron loss of only the single sheet P
p
can be calculated.
Yoke Comp. comes into effect when Yoke Comp. is Enabled, as explained in

4.15. When Yoke Comp. is
Disabled, testing is completed after the 1st measurement.
Still,
Yoke Comp. does not necessarily work at all times . In order to make the magnetic flux density B
ya
of
the double-yoke in the 3rd measurement equal to the magnetic flux density B
ya
of the measuring yoke in the
2nd measurement, this instrument controls the amplitude of the signal generator precisely and adjusts the
excitation current i
1b
sent through the double-yoke. However, the generator cannot be controlled when this B
ya
is extremely small. When a warning message is displayed and the 3rd measurement does not proceed after the
2nd measurement, it is usually the case that this B
ya
is extremely small (i.e., measurement conditions are such
that the core loss related to the measuring yoke is extremely small).
Fig. 2-4 Summary of the measurement principles
P
p
=
1
T
∫ H
p
dB
p
dt
dt
T
0
Signal
generator
Shunt resistor
Relay 1
B Coil
Single sheet
Excitation
coil
Measuring yoke
Double-yoke
Relay 2 Relay 3
B Coil
B Coil
Excitation
coil