For a given current flow, a proportional
magnetic field is produced around the current carrying conductor.
NK Technologies current sensors measure
this field using one of two technologies. For DC currents, we
use "Hall Effect" while for AC currents, we use "Inductive"
technology.
The Hall Effect sensor has a core, Hall
Effect device and signal conditioning circuitry. The current
conductor passes through a magnetically permeable core that
concentrates the conductor's magnetic field. The Hall Effect
device is mounted in the core at a right angle to the concentrated
magnetic field. A constant current in one plane excites the
Hall device. When the energized Hall device is exposed to
a magnetic field from the core, it produces a potential difference
(voltage) that can be measured and amplified into process
level signals such as 4-20mA or a contact closure.
The Inductive sensor has a wire-wound core
and a signal conditioner. The current conductor passes through
the core that magnifies the conductor's magnetic field. AC
current constantly changes potential from positive to negative
and back again, generally at the rate of 50 or 60 Hz. The
expanding and collapsing magnetic field induces current in
the windings. This secondary current is converted to a voltage
and conditioned to output process-level signals such as 4-20mA
or contact closures.
Link to Sensors
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