The PNP-type transistor position indicator sensor detects and is activated when the magnetic field generated by the top of the Super-Seal valve actuator aligns with the sensor. A green LED illuminates when the sensor is triggered (the NPN-type sensor has a red LED). In addition to providing visual confirmation of the valve's state (whether it is open or closed), the PNP sensor can also be used to switch or trigger an auxiliary device.
Super-Seal valves have two position indicator sensor slots in their valve heads, one long, one short. This sensor is activated and illuminates when:
- the valve is open and the sensor is in the short slot.
- the valve is open and the sensor is positioned at the top of the long slot.
- the valve is closed and the sensor is positioned at the bottom of the long slot.
To correctly adjust the sensor, slide it into one of the sensor slots (set screw facing out). Energize the solenoid to open the valve. Slide the sensor up and down in the slot until the LED illuminates. With a small flat head jeweler's screwdriver, tighten the sensor set screw to secure it in place.
The PNP semiconductor sensor has three conductors. It is powered by an external power supply of 5 - 30 VDC and requires a series resistor connected between DC negative and the emitter conductor to limit the current through the green LED (maximum 20mA). The load on this semiconductor sensor need not be a resistor. It can be any load, such as a fan or a relay, as long as the load is rated for the same voltage as that supplied to the sensor, and the load's current draw is less than 200mA, the maximum allowable. For example, if the sensor is supplied with 12 VDC, a 12 VDC rated fan can be substituted for a resistor, as long as the fan's inrush current does not exceed 200mA. A protection diode is needed for inductive loads. These semiconductor sensors are recommended to switch or trigger auxiliary devices through relays, since most small relays have coils which require less than 200mA. There is little perceived reduction of LED intensity when using a non-resistor load.
If using a resistor, the basic calculation for the correct value which yields maximum LED brightness is:
R = 50 (E-2)
where R is the resistor value needed, and E is the operating voltage.
Please see the brochure for sensor technical specifications, wiring, and suggested resistor values at some common voltages. Download the User Manual for information about wiring multiple position indicator sensors, and for complete information about the Ideal Vacuum Super-Seal family of pneumatic bellows valves and available options.
