Installation, Operation and Service Manual
LKAT Plus EMC
© 2018 DynAmp, LLC
Page 17
047331 A
5. THEORY OF OPERATION
5.1
GENERAL
The LKAT Plus system uses open-loop, open-path (OLOP) technology to convert the
magnetic field associated with a current carrying conductor into an isolated milliampere
current loop output. This output is scaled to be proportional to the primary conductor current.
In addition, a local digital display of the primary bus current (in kiloAmperes) is visible when
the optional RMS Display pc board is added to Metering Unit.
Each Measuring Head is a sealed unit and is not designed for repair in the field. However, a
working knowledge of the LKAT Plus system theory of operation will help facilitate timely and
accurate diagnosis in the event of problems.
5.2
OLOP TECHNOLOGY
The term “open-loop” means that the magnetic circuit does not generate an opposing
magnetic field to null the field produced by the primary conductor inside the Measuring Head.
The term “open-path” indicates that the sensor is an air-core design, without magnetic core
material.
The LKAT Plus system operation is based on Ampere’s Law, which states: “the line integral of
B (magnetic flux density) around any closed path is equal to
µ
O
I (permeability multiplied by
current)”. In practical terms, this means that integrating a closed path around a primary
conductor will yield a value proportional the net primary current.
This integration is implemented using a specific array of Hall Effect ICs. The LKAT Plus
system effectively minimizes errors typically present in other open-loop sensors: zero drift,
thermal drift, position sensitivity, and susceptibility to external magnetic fields. The absence
of a magnetic core practically eliminates errors due to saturation, hysteresis, and core set
(remanence) commonly associated with ferrite material.
A generalized block diagram of the LKAT Plus system is shown in Figure 5.1.
