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Monitor SafePoint cut sheet 253P
SafePoint® “Truly” Fail-Safe Rotary Paddle Bin Monitor
Features & Advantages
Self-validating, “truly” fail-safe means that sensor output relays revert to a safe state upon both power loss and if an internal failure of the sensor itself is detected.
Patented magnetic sensing technology using Hall-Effect/magnetics (instead of optics)for maximum immunity to dust ingress into enclosure.
External status LED for local indication that is viewable through wide angle lensindicating both sensing and diagnostic status (not available for Haz Loc version).
Motor shut-off feature maximizes sensor life.
DC voltage model uses a brushless AC motor with a voltage convertercircuit to provide long motor life. See Bulletin #226A for more information.
Ordinary location and Hazardous location models are available.
Rugged powder coated cast aluminum housing with twist on/off cover provides easy and ample wiring access
Principle of Operation
The SafePoint® rotary paddle bin monitor is fundamentally a torque detector which provides an output switched condition when the
resistance of the material surrounding the paddle is greater than the drive mechanism used to rotate the paddle. In addition, the
SafePoint integrates “self-validation” fail-safe mechanisms which continuously test the health of its internal operation thereby assuring
operator of sensor’s ability to provide reliable level detection.
The rotary paddle bin monitor is installed to a vessel wall with a paddle protruding into vessel. A low-power, low-speed synchronous
motor drives a paddle which rotates freely in the absence of material. When the paddle rotation is impeded by the presence of material,
the motor internally shifts a magnet in proximity to electronics. This engages a relay whose outputs are made available for customer
connection to a control system. A moment later, the bin monitor switches off the motor to prolong its life. When the material level drops
below the paddle, a spring returns the motor and corresponding magnet to its original position, and the electronics re-energize the
motor, re-establishes paddle rotation, and returns relay to its normal non-actuated status.
The “self-validation” fail-safe capability is achieved through continuously monitoring the rotation of a magnetic disk that is located
between the paddle and all other operating mechanisms (including the clutch, motor and all electronics). If the electronics ever detects
that lack of rotation of this magnetic disk when no material is present, then the FAULT relay will change state indicating a sensor failure
of some sort.
Sensitivity of the rotary paddle bin monitor is determined by the number of paddle vanes (single, 2-vane, 3-vane, etc) and the spring
tension setting within the sensor.