Installation, Operation and Service Manual
LKP Series 4 Channel OEM
© 2019 DynAmp, LLC
Page 19
041593O
5. THEORY OF OPERATION
5.1 GENERAL
A thorough knowledge of the LKP Series 4 Channel OEM theory of operation is essential for
efficient product familiarization. In figure 5.1, a portion of the Measuring Head is shown to
illustrate the magnetic-null principle used in all LKP Series 4 Channel OEM current measuring
equipment.
5.2 MAGNETIC SENSOR (NULL DETECTOR)
The magnetic sensor produces a voltage output proportional to the difference between the bus
field and the feedback field. The sensor output is amplified and is returned to the magnetic
circuit in the form of feedback current. This current is passed through 5000 turns to produce
the feedback field.
Figure 5.1
Magnetic Null Detector Diagram
5.3 MEASURING HEAD
The Measuring Head contains many magnetic sensors and feedback coils. Each set of sensors
and the adjacent coils plus the associated amplifying section of the Metering Unit is termed a
channel. Each channel responds nearly independently of the other channels to null the bus
field in its own section of magnetic core. However, after passing through their respective coil
groups, all channel currents are summed to produce the output current. This current, which is
always in the ratio of 1 A to 5000 A of bus current, is passed through shunts to develop
voltages for the proportional outputs. The output current itself is also available at the output
terminals that are jumpered if not used.
