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down the amplifier output and to ignore any momentary increase in level
caused by the patrons when the power to the amplifiers has been removed.
However, the function of the “Electronic Orange” is not so much to interrupt
entertainment as to provide adequate notice of excessive levels in order that
they may be controlled to below the required maximum. The warning beacon
gives up to 12dB warning that the trip level is being approached.
Other features include a three colour LED bar graph display showing SPL
(sound power level) which makes monitoring the level easy; a choice of
standard “A” weighting or “B” weighting characteristics which is more
effective for bass control. Outputs are available for remote analogue or digital
displays. In addition to the standard measurement microphone input the
facility is provided for an external trigger input from, for example, a contact on
a fire door. In addition, the device is fitted with an anti-tamper circuit and the
cause of a cut-off is clearly indicated by the “Level”, “Microphone”, and
“External” indicators.
Installation
WARNING:
THE GA904 SHOULD BE WIRED TO THE MAINS POWER SUPPLY BY A
QUALIFIED ELECTRICAL INSTALLATION ENGINEER.
MAINS VOLTAGES ARE PRESENT IN THIS UNIT.
The warning above applies to any work carried out on the main body of the
GA904 unit, as live terminals are exposed inside the box.
The only exception to this rule is the area inside the hinged door on the left of
the instrument, which is provided to allow the appropriate authority to make
any adjustments to the trip time and level which are found necessary. There
are no mains voltages present in this section of the GA904 enabling the unit
to be set up in safety. For more information see Section 4.
Power Rating Limitations
The maximum rating of the GA904 control box is 30 Amps. This is limited by
the current switching capacity of the relay inside the unit. Hence the unit can
switch a mains ring fused at 30 Amps.
However the maximum current is also limited by the cable running to and
from the control box, hence the mains input must incorporate a fuse no
greater than the current carrying capacity of the cables.
