Riken Keiki PT2-177, Operating Manual

Page: 32 / 56

6 Operations and Functions 6-3. External output operation
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6-3. External output operation
Signal Transmission System Electric current transmission (non-isolated) 4
– 20 mA
Transmission Path CVVS equivalent
Transmission Distance CVVS equivalent 1.25 sq: Maximum 1.25 km
Connection Load Resistance Below 300
Ω
1 Detection Mode
(No Alarm) 4 - 20 mA (concentration output)
2 Detection Mode
(Gas Alarm) 4 - 20 mA (concentration output)
3 Initial Clear Depending on the setting of section 4.
2.5 mA setting: 2.5 mA
4 mA, HOLD, 4 - 20 mA setting: Equivalent to AIR
value (17.4 mA)
4 Maintenance Mode 2.5 mA setting: 2.5 mA
4 mA setting: Equivalent to AIR value (17.4 mA)
HOLD setting: The previous value retained
4 - 20 mA setting: 4 - 20 mA (concentration output)
5 Alarm Test Output ON setting: 4 - 20 mA (concentration output)
Output OFF setting: The previous value retained
6 Fault Alarm 0.5 mA (Fixed)
7 INHIBIT Depending on the setting of section 4.
2.5 mA setting: 2.5 mA
4 mA, HOLD, 4 - 20 mA setting: Equivalent to AIR
value (17.4 mA)
8 Power Off 0 mA
Example of Gas Concentration and External Output
0 - 25 vol% (Oxygen deficiency alarm specification)
Detection mode
Maintenance mode
Suppression value
Gas concentration
External output
17.4 mA
4 mA
20 mA
22 mA
Full scale
0
CAUTION

The 4 - 20 mA output is already adjusted. In case of over scale, an output will not exceed 22
mA.

Output during INHIBIT or initial clear is based on 4 - 20 mA output setting in the maintenance
mode.
In particular, when the detector is started or the specification is changed, be careful about 4-20
mA output setting. Understand how the detector functions, and take actions, if necessary, so
that the signal receiver side can prepare to avoid false alarms.