Siemens SITRANS WM300 MFA, Operating Instructions Manual

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SITRANS WM300 MFA
Operating Instructions, 08/2018, A5E45090709-AA
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Technical Reference
A
A.1 Principles of Operation
SITRANS WM300 MFA
SITRANS WM300 MFA is a highly sensitive, dual setpoint motion sensor alarm unit, used
with MSP and XPP probes. The probe detects an increase or decrease in the speed of
rotating, reciprocating, or conveying equipment and sends the information to the SITRANS
WM300 MFA. The SITRANS WM300 MFA works with a pre-amplifier which can be internal
to the motion sensing probe, or remote from the motion sensing probe. Pulses generated
from the probe are continually compared to the adjustable setpoint.
Probe
The Milltronics probes work on the principle of Faraday’s Laws of Electromagnetic Induction.
When a ferromagnetic object enters the probe’s permanent magnetic field, it distorts the flux
causing it to cut the coil windings and generate a voltage. This voltage is proportional to the
strength of the magnet and the number of wire turns in the coil (constant in the Milltronics
probes) and the speed at which the ferrous target passes through the flux. The generated
voltage is also inversely proportional to the square of the distance between the target and
the probe.