Hioki RM3545-02 - Page 340

Appendix 12 JEC 2137 Induction Machine-compliant Resistance Measurement
A28
Standard JEC 2137 specifies the determination of resistance values according to the fol-
lowing formula:
Transforming Formula 1 provides the following:
............. Formula 2
On the other hand, Formula 3 shows the temperature correction process with the RM3545.
So the temperature coefficient to be set is determined as shown in Formula 4.
................................ Formula 3
.................................................... Formula 4
For example, if the reference temperature is 20°C, set the temperature coefficient for the
instrument as follows.
Appendix 12 JEC 2137 Induction Machine-com-
pliant Resistance Measurement
R
t
R
= R
t
T
×
t
T
+ k
t
R
+ k
......................................... Formula 1
R
tR
Winding resistance at reference temperature t
R
R
tT
Measured value of winding resistance at t
T
t
R
Reference temperature [°C]
t
T
Temperature of winding during measurement [°C]
k Constant (235 for copper wire)
R
t
T
R
t
R
=
t
T
+ k
t
R
+ k
=
1
(
t
T
− t
R
)
1
t
R
+ k
1+
R
t
R
=
1 + α
t
R
× (t
T
− t
R
)
R
t
T
α
t
R
=
t
R
+ k
1
α
t
R
=
t
R
+ k
1
=
20 + 235
1
= 3922 [ppm/°C]