11
４ − ４ ． Caution in the system engineering
Unstable power and noise may cause error of performance and alarm.
For the system to use this unit, it is required to make design based on this
manual descriptions.
（１）
Stable power used
While the system gets stable at power failure, the external output and alarm contact 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 unit .
Power voltage
100〜240VAC, 50/60 Hz
Power failure
tolerance time
Approx 50msec.
（For power failure of 50msec, it re-starts）
To warrant the continuous operation, install the standby battery
outside.
Others
Do not contact with power involving high power load and high
frequency noise.
According to requirement, use line filter and separate it from
noise source.
（２）Designing to consider radiation
When install the closed self-standing control panel, mount the fans in the upper and lower part.
（３）Lightning measures
Lightning surge
There is the problem “Lightning”. When make outdoor wiring of cable at factory or plants etc or
when make a parallel wiring in the same duct with the cable in from outdoor even at the indoor
wiring. 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 or laid in the underground, it is impossible to prevent
the inductive lightning surge generating from the thunder.
Lightning
measures
There is not the complete countermeasure for it but the following method can be considered.
Make the suitable treatment accordingly.
a)
The transmission signal route is arranged for connection by the optical fiber cable etc.
b)
Countermeasure by the lighting 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 (Protection resistor, zero diode etc.) and is designed
to protect the apparatus. But as the signal may be attenuated due to the lightning arrester,
check the action and it is required to use.
Grounding
Surge noise shall be generated from the thunder lightning or except it.
To protect detector from these cause, be sure to make grounding.
＊
In the lightning rod, there is the circuit to remove the surge voltage to be a cause of damage
from field instruments.
By installing the lightning rod, the signal may be attenuated. When install the lightning rod, it
is required to check the performance in advance.
CAUTION
