D0920 Arc-Detection Unit Rev. 0-D-070616
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2. OPERATION
2.1 Front-Panel Controls and Indication
2.1.1 Sensor Adjust
The D0920 sensitivity default is 6 mA of sensor output current to cause a trip. This is equivalent to
a light intensity of 12,000 lux on a single sensor or 6,000 lux on each of two sensors. This means
that the total light intensity on all sensors installed has to exceed 12,000 lux to cause a trip.
The sensitivity is adjustable from 1 to 12 mA (2,000 to 24,000 lux) using the SENSOR ADJUST
dial.
2.1.2 ACTIVE and TEST Mode
The D0920 has a two-position switch, marked ACTIVE and TEST.
The green LED labelled ACTIVE indicates that the ACTIVE mode has been selected. In the
ACTIVE mode, the D0920 is configured for normal operation and will trip the trip coil if an arc flash
occurs. In ACTIVE mode, the relay K2 contact (terminals 11 and 12) will be open unless supply
voltage is removed. Ensure that the D0920 is normally set to the ACTIVE mode.
The red LED labelled TEST indicates that the TEST mode has been selected. In the TEST mode,
the D0920 and any connected point sensors can be tested without tripping the trip coil. In TEST
mode, relay K2 will be closed. See Fig. 4.
2.1.3 Power
The green LED labelled POWER indicates the presence of supply voltage.
2.1.4 Tripped
The red LED labelled TRIPPED indicates a trip.
A trip remains latched until the RESET button is pressed. External circuit breakers or other
devices will have to be reset manually.
2.2 Auxiliary Relays
2.2.1 Trip Indication
The D0920 has one normally-open contact (K1, terminals 9 and 10) that closes during a trip. It can
be used for trip indication.
2.2.2 Remote Signalling
The D0920 has one normally-closed contact (K2, terminals 11 and 12) that closes during loss of
supply, or when the D0920 is in the TEST mode. It can be used for remote signalling.
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