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Limit Switches
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offers various kinds of
"limit switches"
on our valve and dynamic feedthrough products.
Here are some brief descriptions of
what they are and how they work --
How it Works:
Reed switches contain hermetically-sealed reeds or contacts. When a
magnet attached to the actuator on the valve or feedthrough moves close to
the
switch, the reeds become magnetized and the normally open contacts
will close or pull in, completing the circuit. When the magnet moves
away from the switch, the contacts will open or drop out, breaking
(opening) the circuit.
How it Works:
A micro switch is a mechanical switch, requiring physical contact
for operation. When contact is made with the switch trigger, the
switch contacts are activated.
All
micro switches used on Huntington
products can be wired as "normally open" or "normally
closed".
When wired as "normally open", with the switch in its
rest position (not activated), the circuit is open, no current flow.
When activated, the contacts are closed, completing the circuit.
When wired as "normally closed", with the switch in its
rest position (not activated), the contacts are closed, completing the
circuit. When activated, the contacts are opened, breaking (opening)
the circuit.
How it Works:
In operation, a constant current is passed through the Hall sensor.
When a magnet attached to the actuator on the valve or feedthrough
is not directly below the sensor, the current (flow of electrons) is evenly
distributed across the chip. With an equal number of electrons at the
chip edges, no potential difference exists at the output. When the
magnet is directly below the sensor, the electron flow is distributed
by the magnetic field to one side of the chip causing an imbalance in
the electron concentration at the edges. This creates a potential
difference, the Hall voltage, at the output. This Hall voltage is
detected and amplified to control a switching output transistor.
What is the difference in Hall
Effect switches.....sinking vs. sourcing?
Sinking vs. Sourcing
Sinking Switches
are applied to the negative side of a load. When the switch is activated,
the negative (ground) is connected, completing the circuit.
Sourcing Switches
are applied to the positive side of a load. When the switch is activated,
power is connected, completing the circuit.
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