CHARGE FAILURE MONITOR (Type 1 667 series) CIRCUIT FUNCTION & SETTING INFORMATION.
DATA SHEET AVAILABLE THROUGH THIS LINK.
Operating Principal. Use in accordance with supplied product documentation.
The 667 Charge Failure monitor is designed to detect charging current from thyristor based charging systems or from a suitable dc current sensor and de-energise a relay if the measured current falls below a pre-set limit.The unit functions by comparing a reference voltage generated by R22, CR3, VR1 and R8 on pin 2, (inverting input) fitted to the charge failure monitors pcb, to a signal derived an external current sensing device (shunt, sensor or current transformer) which is fed onto pin 3 (non-inverting input) via R10. Rectified current transformer or shunt/sensor derived signals are smoothed before application to the op amp input pin to avarage out any ripple.
When pin 1 switches from high to low, a negative going pulse on pin 2 of U1 triggers the timing circuit into count mode. The signal voltage on pin 5 will drop to approximately 3VDC whilst the potential on pin 6 remains at 2V DC.
At the end of the preset timed period the output signal from pin 1 of U1 switches from low to high, forcing pin 6 (inverting input) of the op amp more positive than pin 5 non-inverting input). The output voltage from pin 7 switches from high to low, pin 5 is pulled down to approximate 1VDC via D4 & R20 and T1 is switched off causing the relay RL1 to de-energise.
The 16V electronic supply is generated by components CR1 and ZD3 whilst C4 and C5 smooth the rail and maintain a steady dc level devoid of noise and switching spikes that can occur on the dc supply pins 2 (negative) and 10 (positive).
The potentiometer VR1, adjusts the reference voltage on pin 2 (inverting input) of the op amp which adjusts the charging current detection level. Potentiometer VR3, adjusts the frequency of the timer oscillator which provides adjustment of the fault detection - relay de-energisation delay. The third potentiometer VR2, is used where two separate detection levels are required.
SETTING THE CHARGE FAILURE MONITOR.
To set the Charge Failure Monitor, the batteries must be fully charged and connected to a charger delivering float maintenance current only.
The potentiometer VR1 is adjusted anti-clockwise until the red PCB mounted led illuminates and the green led is off. The potentiometer should then be slowly adjusted until the LED's change state. Verification of a correct setting is made by switching off the mains supply. The red led should switch on, the green led should switch off and after a short delay, the relay should de-energise.
SETTING THE FAULT DETECTION - RELAY DE-ENERGISATION DELAY.
Using a suitable counter, measure the frequency of the oscillator on C3/R15/VR3. Adjust VR3 until the reading displayed on the instrument is at the required level.
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