RKI Instruments GD-70D Series - Manual (Page 39)

4 Detection Mode 4-3. External output operation
- 39 - GD-70D
Example of Gas Concentration and External Output
4 - 20 mA Specification
(Maintenance output: 2.5 mA setting)
CAUTION
<< 4 - 20 mA Specification>>
• 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.
Be careful for a possible lower output which drops as low as 2.5 mA during initial clear when OSU (L
alarm) is used. In particular, this occurs when the detector is started or the specification is changed.
Understand how the detector functions, and take actions, if necessary, so that the receiver side can
prepare for false alarms.
<
Example of Items which Requires Special Precautions>
Maintenance output setting Sensor unit Details
2.5 mA Use OSU (L-LL, L-H). Output 2.5 mA during maintenance or inhibit.
Possibility of false alarm in the upper unit (L
alarm)
Specification change
(To OSU - 0 - 25 vol%) In case of a change from another principle
(H-HH), 4 mA (equivalent of concentration zero)
is used until the change is confirmed "C-02". 4 mA, HOLD, 4 - 20 mA
Specification change
(From OSU - 0 - 25
vol%) In case of a change from 0 - 25 vol%
(L-LL,L-H), 17.4 mA (equivalent of approx.
84%FS) is used until the change is confirmed
"C-02".
2.5mA
4mA
20mA
22mA
Full scale
Gas concentration
External output
Zero
suppression
Detection mode
Maintenance mode