Deckma Hamburg OMD-2008, Instruction Manual

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3.13 Specification Internal Clock
The IMO resolution MEPC.107(49) requires the 15 ppm Bilge Alarm to record Date, Time,
Alarm Status, and “Separator Status”. To do so, the instrument has an internal clock. The
internal clock circuitry is “state of the art”, with only a few ppm derivations over the entire
range of operational conditions. The instruments are adjusted within ± 2 minutes of
GMT (Greenwich Mean Time) in production.
In many cases derivations of the internal clock tend to cancel out each other, but in some
cases the instrument accumulates more derivation. If the difference vs. GMT is small
(minutes), it should be of no further concern. There are no requirements for clock
accuracy in MEPC.107(49). If the derivation is many minutes, it is recommended to
eventually (e.g. annually) document the derivation, so that it is always possible to relate
recorded events to real time. If the derivation is huge (hours or more), or if it occurs
suddenly or erratically, or if a completely useless time information is displayed, some
defect or damage of the internal clock has to be assumed and it would be necessary to
exchange the Computer Unit and send it for diagnosis and repair. There is no way of
adjusting the internal clock on site.
3.13.1 Internal Back-Up Lithium Thionyl Chloride Battery
Further the PCB of the computer unit is equipped with an internal back-up lithium thionyl
chloride battery, for the internal clock, if the computer unit is out of power.
The internal lithium battery of the OMD-2008 Computer Unit has a low self-discharge
(<1% per year) and should have a calculated lifetime over 20 years, if handled properly.

In case the lithium thionyl chloride battery fails, it must be replaced by a qualified
technician in our factory. Please do not exchange the lithium battery by yourself. The
battery cannot be replaced with a standard battery.
See Section Disposal for more information.