Solenoid supervisory system
Systems and methods for a solenoid supervisory detection system which can detect the presence or absence of a solenoid plunger within a solenoid coil. These systems can be used to verify correct reassembly of a solenoid valve after it has been disassembled for testing.
1. A system for detecting the presence of a solenoid plunger within a solenoid winding, the system comprising:
a solenoid coil assembly comprising said solenoid winding;
a solenoid plunger assembly comprising said solenoid plunger;
an electric circuit connected to said solenoid winding, said circuit comprising:
an isolated power supply;
a Colpitts oscillator;
a microcontroller comprising:
a low pass filter, rectifying and attenuating output of the oscillator;
a non-inverting amplifier, amplifying output of the low pass filter; and
a comparator for comparing output of said amplifier against a set voltage;
wherein said microcontroller supplies two different types of signals to said solenoid winding; and
a monostable multivibrator acting on output of said comparator to drive a FET opto-coupler.
2. The system of claim 1 wherein said microcontroller detects resultant waveforms from both said signals.
3. The system of claim 2 wherein a first of said signals is used to detect said solenoid winding's inductance.
4. The system of claim 3 wherein said first of said signals is a single, positive going, fixed voltage, fixed time pulse.
5. The system of claim 4 wherein a second of said signals is used to detect said solenoid winding's capacitance.
6. The system of claim 5 wherein said second of said signals includes coded and/or modulated signal packets.