Xtralis VESDA VLC-400, Руководство по эксплуатации продукта

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VESDA by Xtralis VESDA VLC-400 Product Guide
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2.4 Functions
2.4.1 Loop isolation
The VESDA VLC-400 includes a loop isolator designed to maintain the loop configuration in the event that a
short circuit fault occurs. If a short circuit appears on the loop, the loop isolator opens that connection and
isolates that segment until the problem is rectified.
2.4.2 Loop loading
The maximum number of devices that can be supported on a single loop is 126. Each device has a loading of
less than 220µA.
2.4.3 Power supply monitoring
The VESDA VLC-400 provides an input circuit to monitor an external power supply unit (PSU), if applicable.
During normal operation the PSU presents a normally open contact with a 47K ohm end of line (EOL) resistor
across it. This 47 KO resistor sets the supervision current in the field wiring between the detector and power
supply.
When the PSU detects a fault condition the fault contact will be closed thus causing a short on the input
circuit, which will cause the VESDA VLC-400 to transmit a fault to the fire panel.
At least one VESDA VLC-400 detector or other monitoring device should monitor each PSU. If external
monitoring is not connected to the detector then ensure the 47KO EOL resistor is fitted to the PSM terminals
on the termination card.
2.4.4 Drift compensation
The VESDA VLC-400 does not require drift compensation. The drift value is set to 0 for an aspirating type
detector and 16 for an optical type detector.
2.4.5 AutoLearn
AutoLearn is the process of monitoring the average smoke obscuration levels in an environment in order to
automatically set alarm thresholds that are appropriate. This assists in ensuring the earliest possible warning
of a fire condition while minimizing the risk of false alarms.
2.4.6 Relay output
The relay output is configured via Xtralis VSC using the normally open or normally closed contacts. The relay
can be configured to follow either the Fire LED or allow the relay output to be controlled directly by the fire
panel.
If the detector relay output is to be used for the purpose of signalling an alarm condition, it is generally
advisable to configure it to follow the Fire LED (bit 2) rather than the remote LED/relay (bit 0) signal from the
FACP. It is only necessary to configure it to follow the remote LED/relay signal if the relay is required to signal
anything other than the individual Compact alarm condition. This is only relevant where the FACP has the
capability to customize the function of the relay output (as if it were an optical detector on a relay base).
NOTE: If the LED/relay signal (bit 0) is intended for the operation of a remote LED, many FACP’s limit the
number of remote LED’s that may be illuminated in order to minimize the alarm current. If in doubt, please
contact the fire control panel manufacturer.
2.4.7 Remote LED
The remote LED may be configured via Xtralis VSC to mimic the Fire LED on the VESDA VLC-400 or be
directly controlled by the fire panel.
If the remote LED is not illuminated by an alarm condition it will flash once every 30 seconds to indicate fault-
free operation.