PT1E-0930
13
４－４－４ Alarm contact
・Alarm contacts shall be used only for external buzzer and alarm light, and do not use it for the
controlling use (such as solenoid valve control etc).
When control the external load, the bad influence may be given to the system according to the load characteristics.
In such case, the following countermeasure shall be taken to stabilize the action and protect the contents.
・Relayed by the low voltage relay and operate by connecting CR circuit (Spark Killer: SK) (Diode etc for DC) suited
for relay coil directly to relay.
・Add CR circuit to the load side of relay on the request.
Reference: By the condition of load, CR circuit may be better to install in the contact side but it is required
to put in by checking the action of load.
ＳＫ：Surge absorption filter
－How to think alarm contacts against inductive load－
The spec for alarm contact of EC-592 is described by the conditions of resistive load.
When use the inductive load for alarm contacts, the very high reverse electromotive voltage may be generated and
the following trouble tends to be produced.
・Contact part of relay is melted adhesively and the contacts can no work.
・High voltage is put inside of indicator/alarm unit and then, electrical parts may be damaged.
・As it is big noise, the trouble action may be taken by the reckless drive of CPU.
Irrespective of inductive load, there is the possibility of unforeseeable noise instruction for contact.
Above trouble may be generated.
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SK
L
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d
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SK
C
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l
Power supply
Power supply
Relay
(Low pressure relay)
Alarm contact
ＲＭ－５９３
CAUTION
（FOR USE OF NORMALLY-CLOSED CONTACT）
Normally-closed contact (Break contact) at non-existing condition may change to open contact in a
moment due to physical shock.
Whenever alarm signals from gas detectors are used with normally-closed contact, please put
delayed-circuit (for about one second) to receiver side of normally-closed contact to avoid
such phenomenon.
