RKI Instruments RM-5000 Series Multi-Unit Case - Manual (Page 15)

4 How to Use 4-4. Precautions for system designing
- 15 - RM-5000 Multi-unit Case
4-4. Precautions for system designing
Using a stable power supply
The external output and alarm contact of the buzzer unit may be activated when the power is turned on, The
external output and alarm contact of the multi-unit case may be activated when the power is turned on,
when momentary blackout occurs, or while the system is being stabilized. In such cases, use a UPS
(uninterrupted power supply), or take appropriate actions on the receiving side of output signals.
The multi-unit case must be provided with the following power supply.
Power supply
voltage
100 - 240 VAC +/-10% (Terminal voltage of the multi-unit case)
Allowed time of
momentary blackout
Up to 100 milliseconds
(To recover from the momentary
blackout for 100 milliseconds or more,
restart the multi-unit case.) Example of actions
To ensure continuous operation and
activation, install a UPS (uninterrupted
power supply) outside the multi-unit case.
Others
Do not use it with a power supply of
large power load or high-frequency
noise. Example of actions
Use a line filter to avoid the noise source
if necessary.
Heat radiation designing
When it is installed in the closed instrumentation board, attach ventilation fans above and below the board.
Introducing protective measures against lightning
If cables are installed outside the factory/plant, or if internal cables are installed in the same duct as the
cables coming from outside the factory/plant, "lightning" will cause problems. Because lightning acts as a
large emission source while cables act as a receiving antenna, devices connected to the cables may be
damaged.
Lightning cannot be prevented. Cables installed in a metal conduit or under the ground cannot be
completely protected from inductive lightning surge caused by lightning. Although complete elimination of
disasters caused by lightning is impossible, the following protective measures can be taken.
Protection
against lightning
Take appropriate measures in accordance with the importance of the facilities and the
environment.
• Connect the transmission signal route by using optical fiber.
• Provide protection by a lightning arrester (cable safety retainer).
(Although inductive lightning surge can be transmitted through the cable, it is
prevented by installing a lightning arrester before the field devices and central
processing equipment. For information on how to use a lightning arrester, please
contact the manufacturer.)
Grounding
In addition to lightning, there are more sources of surge noise. To protect units from
these noise sources, the units must be grounded.
* The lightning arrester has a circuit to remove a surge voltage which damages field devices, so that
signals may be attenuated. Before installing a lightning arrester, verify that it works properly.
CAUTION
An unstable power supply and noise may cause malfunctions or false alarms.
The descriptions in this section must be reflected on the designing of a system using the multi-unit
case.