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Figure 2-1 Ball Float Type Operating Principle Figure 2-2 Displacer Type Operating Principle
2.2.2 Float Type Operating Principle
With the float ball as the induction element, the float ball is rigidly connected with the magnetic rod.
When the level rises, the ball float drives the magnetic rod upward into the magnetic field area of
the magnetic switch assembly. Through magnetic induction or magnetic coupling, the switch
contacts are switched on or off. When the level is lowered, the float ball moves downward and
drives the magnetic rod away from the magnetic field of the magnetic switch assembly. Then the
magnetic controlling switch returns to its original state, or the offset magnetic steel returns to a new
equilibrium position under the action of gravity and makes switch contact on or off to realize the
level that can be controlled and given an alarm.
2.1.3 Displacer Type Operating Principle
With the displacer as the sensing element, the displacer hangs on a spring through the suspension
rod. When the level is raised, the liquid contacts with the displacer and the displacer creates a
buoyancy. With the buoyancy, the pulling force on spring is smaller, and the spring shrinks, driving
the magnetic rod upward into the magnetic field area of the magnetic switch assembly. By magnetic
induction or through magnetic co-operation, magnetically controlled switch or bias magnetic steel
drives the switch contacts are switched on or off. When the level is lowered, the floating force is
reduced, and the spring is subjected to a larger pull force. The spring drives the magnetic rod out of
the magnetic field of the magnetic switch assembly. The magnetically controlled switch restores the
original state or bias magnetic steel, under the self-weight, back to the new equilibrium position,
making the switch contacts switched on or off for the control or alarm of the level.
