Iwatsu SS-663, Instruction Manual

Page: 21 / 34

Chapter 3 Measurement Principle
17
3.2 Main Unit
As illustrated in Figure 3.2, the electromotive force e induced in Section 3.1
is brought in the input part of the main unit through the sensor cable.
As explained in Equation 3.1 in Section 3.1, the electromotive force e is
integrated by the integrator of the main unit, because it is the time
differentiation of the current.
The output voltage of the main unit Vout is expressed by Equation 3.2.
…… (3.2)
A:
Constant determined by the component constants of
the circuit of the main unit
The output voltage of the main unit (current waveform) is observed by an
oscilloscope and other monitoring devices through the BNC cable.
As expressed by the following Equation 3.3, the voltage component Vout
observed by monitoring devices can be converted to the current I with a
sensitivity S (mV/A) described on the label affixed to the back of the main
unit.
I = Vout
／
S
…… (3.3)
The current I (current waveform) of the conductor to be measured is
determined by the measurement principle described in this chapter.
Figure 3.2 Illustration of Rogowski Coil Operation
Main unit (in the dotted area)
Sensor cable (coaxial)
Input part
Integrator
Output part
BNC cable (coaxial)
Observation with an
oscilloscope (not included)
and other monitoring
d i