140528/2
Page
31
of
32
14
Theory of operation
14.1 Basic principle of ITZ FLEX ULTRASTAB current transducers
The ITZ FLEX ULTRASTAB current transducers are delivered in a series
covering galvanic isolated measurements of currents from DC to 500 kHz
ranging from 40 A to 24 kA.
These precision current transducers use a zero flux detector principle
controlling a compensation current which counterbalances the ampere-turns
generated by the primary current. Due to a balanced zero flux detector
principle the output noise level is extremely low by nature and a resolution on
the order of 2 x 10
-8
is achieved.
Below is shown a block diagram of the zero flux detector principle.
The transducer head core1 is the basic body structure. The core2 and core3
are the flux detectors coupled to the zero-flux detector circuitry by means of
the coils L1 and L2.
Coils L1 and L2 are coupled in parallel or series depending on the model, with
opposite phase to reduce any unwanted flux generated in core 1.
Figure 9: Block diagram show ing the zero flux detector principle
