DynAmp LKAT2 - Theory of Operation; General and OLOP Technology

Installation, Operation and Service Manual LKAT
2
+24V
© 2018 DynAmp, LLC Page 19
046404 E
5. THEORY OF OPERATION
5.1 GENERAL
The LKAT
2
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
2
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
2
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 to the net primary current.
This integration is implemented using a specific array of Hall Effect ICs. The LKAT
2
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
2
System is shown in Figure 5.1.