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For battery charger systems with capacitor filtered outputs, the Battery Alarm requires a
choke of
≥
2mH to be fitted at the output of the battery charger to ensure correct operation of
the high impedance alarm (see Figure 1).
In normal operation, the non-urgent (earth fault or high volts cut-off) relay is de-energised and
the urgent relay is energised, thus providing a ‘fail to safety’ feature.
If the supply voltage falls below 66% nominal for longer than 50 milliseconds, an
instantaneous urgent alarm is given. When the supply voltage returns to above 66% nominal
a ‘power on reset’ occurs after a time delay of 1 second.
Operation
The Battery Alarm derives its power supply from the battery being monitored. The current
consumption is approximately 20mA. Four monitoring functions are provided:
A. Earth fault alarm (positive and negative).
B. Over voltage alarm.
C. Under voltage alarm.
D. High battery impedance alarm.
A common configuration for alarm relay outputs is routing functions B, C and D via a timer
circuit to the urgent relay.
Six LED indicators are provided for diagnostic purposes and under normal healthy conditions
only the one monitoring the power supply is lit.
The LEDs for all four functions listed above will light instantaneously when a fault is detected
and the urgent and non-urgent alarm relays will trip after their preset time delays.
Commissioning
Battery Alarms are available calibrated for other battery voltages between 24V and 220V.
They are designed for flush panel mounting in a cut-out measuring 92mm square (+0.8, –0),
and secured in position with the clamps provided. Before connecting up, ensure that the unit
supplied is suitably rated for the battery installation to be monitored, otherwise damage
could be sustained. Connect the + and – terminals and also connect the E terminal to earth.
Connect the output contacts to the telemetry or other alarm annunciators as required.
After carefully removing the small access window, the front-mounted potentiometers can be
adjusted as follows:
1. High Impedance
Rotate this control anticlockwise until the associated LED is lit, then slowly rotate
clockwise until the LED is just extinguished. This gives maximum sensitivity. Further
clockwise rotation increases the trip impedance.
2. Over Voltage – preset at factory.*
3. Under Voltage – preset at factory.*
* A limited amount of adjustment is possible to suit a particular installation but an
injection test is preferred (apply to factory for details).
Summary of Contents for BA300
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