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2.4 PRESSURE SENSOR CHECK OUT
Background
The pressure sensors used on the Intellisys controllers use a 5 VDC supply and
turn it into a varying voltage signal to the controller. The SE and Original use a
0-50 mv signal and the SG uses a .5-4.5 VDC signal. Both supply and signal
voltages can be measured. The Sensor can also be checked out with it removed
from the unit.
Procedure
Original Intellisys Controller or SE Intellisys
Measure voltage on red and black wire.
Should be 5 VDC+/- .2 VDC.
Measure voltage between white and green: 0 psi = 0.0 mv +/- 5.0 mv.
Disconnect sensor and measure resistance between red and black wire. The
resistance should be 405 to 600 ohms.
Disconnect sensor and measure resistance between white and green wire. The
resistance should be 575 to 1195 ohms.
Disconnect sensor and measure from each wire to the casing of the sensor.
Should read as an open circuit.
SG Intellisys Controller
Measure voltage on red and black wire.
Should be 5 VDC +/- .2 VDC.
Measure voltage white to black: 0 psi = 0.5 VDC +/-.1V (i.e. 1 psi = .01777 VDC)
Disconnect sensor and measure from each wire to the casing of the sensor:
Should read as an open circuit.
2.5 TRIAC OUTPUTS
Background
Triacs can be thought of as a solid state relay operated by a 5 VDC signal. One
of the unusual things about a Triac is that the output voltage cannot be
determined if the Triac is off or on unless there is a load such as a solenoid
connected to the output. It is a good practice to carry a known good
incandescent light that can be connected to the output when testing for output
voltage using a digital voltmeter.
One of the main causes of a failed triac is the coil or solenoid that it operates has
a short circuit causing the current to exceed the capabilities of the triac.
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