RKI Instruments SD-705EC - Manual (Page 8)

PT2E-1140
Be sure to use an optional drip-proof
cover when the detector is to be
installed out of doors.
Caution ！
⑤ Place where the temperature is
below ‐10℃ or +40℃ or more
CAUTION ！
When intending to open the lid, wait for 30 seconds or more after powered OFF
and then, open the lid.
２−３ Cautions for System Engineering
Unstable power supply and noise may cause error of performance and alarm.
For the system to use this detector, it is required to make design based on this manual
description.
(1) Stable power used
While the system gets stable at power on and power failure, the external output
and alarm light may be on and the care for it must be taken. In such case, use
the standby battery or take an appropriate action in the receiver side.
Supply the following power to this detector.
・Power voltage :DC24V±10%
・Power failure tolerance time :Approx. 50msec or less
(For power failure of more 50msec, it re-starts.)
To warrant the continuous operation, install the standby battery outside.
(2) Noise measures according to installation circumstances.
① Lightning（Thunder）surge measures
There is the problem point “Lightning(Thunder)” when installing the detector
outside of factory. If the lightning is a huge generation source, the cable is a
reception antenna and there is the case that cable connecting instrument is
broken. It is impossible to prevent the generation of lightning. If the cable
should put in metal tube, laid in the underground, it is impossible to prevent
the inductive lightning surge generating from the thunder.
There is no complete countermeasure for it but the following method can be considered.
Make the suitable treatment accordingly.
<Countermeasure by the lightning arrester(Cable safety retainer)>
There is the way to install the lightning arrester just before the field apparatus and the
central control station. The position of the lightning arrester installation is at each point
of cable laid out from the outdoor to the indoor.
The lightning arrester builds in the circuit to remove the surge voltage to be the source
for the damage of field apparatus.
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