Carrier Graviner Mk6, Инструкция по установке, эксплуатации и обслуживанию, Страница: 17 / 132

Nov-21 Page 17 of 132 59812-K001 Rev 10
1.4 SYSTEM OVERVIEW
The Graviner MK6 OMD retains the long-established differential measuring system unique to
Carrier Fire & Security Limited, which enables high sensitivity to be used while maintaining the
maximum false alarm rejection. It still uses optical sensing, but light scatter instead of
obscuration. This enables very small Detectors to be used. These are rugged and designed to be
engine mounted using standard oil mist detector ports. As they each have their own means of
sample acquisition no sample pipes are required. Multiple internal light sources ensure that a
single failure will not cause the loss of a Detector. Modular construction means that a faulty
Detector can be replaced in a matter of minutes.
Each Detector continually monitors the oil mist density in the crankspace to which it is
connected. In addition, it self-checks for any internal faults. The Control Panel interrogates each
Detector in turn, notes its address, the oil mist density value and determines the health of the
Detector.
For each engine the average oil mist density from each Detector is calculated and stored. Each
Detector signal is then compared in turn with the stored average. A positive difference (the
deviation) is then compared with a pre-set, but adjustable reference (the deviation alarm level)
for that engine (or Detector). If it is greater than the reference a deviation alarm is indicated.
The stored average level is also compared with a pre-set reference (the average alarm level) and
an average alarm is indicated if the reference is exceeded.
A full system of 64 Detectors over 8 engines has a maximum scan time of 1.2 seconds, but with
alarm priorities that enable the system to respond if an alarm occurs.
The Control Panel separates the information according to engine groups.
The Control Panel incorporates a Liquid Crystal Display (LCD). The Main Display constantly
displays the average oil mist density reading for each engine along with the average alarm level
for each engine. It also enables the individual readings of each Detector on an engine and the
average to be displayed on demand and automatically under alarm conditions.
In the interest of safety, all system controls and alarm displays are located on the Control Panel.
However, to aid fault finding each Detector is fitted with 3 indicator lights:
Green - Power on
Red - Alarm
Amber - Fault
Each Detector also has access to its address set switches.
As all Detectors operate independently, the loss of one by either failure or the need to clean does
not affect the operation of the rest of the system. Individual Detectors, or engine groups, can be
isolated from the rest of the system for maintenance while the rest of the system remains in
operation.
Alarm Philosophy
The system has 3 separate alarms as detailed below
1. Average Alarm - This indicates that the average oil mist levels within the engine are increasing
and that an investigation should be undertaken. This alarm will operate the slowdown/shutdown
and the common alarm relays.
2. Deviation Alarm - This indicates that the level of a detector has increased above the engine
average level and that an investigation should be undertaken. This alarm will operate the
slowdown/shutdown and the common alarm relays.
3. Back Up Alarm - In the event of a failure of either the Control Panel or Detector software, then
the Back Up Alarm will operate the common alarm relay, but it will not operate the
slowdown/shutdown relay. This is an additional functional precaution added by Carrier Fire &
Security UK Ltd which can be connected in any way the customer requires. This is usually
connected to a warning beacon or siren; however, the customer may choose to connect the relay
to another device or to the engine slowdown or shutdown circuitry.