User Manual

23 • Operation Model GD-K77D Operator’s Manu al

4-20mA Output

The followi ng graph illu str at es the re lat ion sh ip between the 4-20m A outpu t and the gas

concentration.

Figure 10: 4-20 mA output vs. Gas Concentration

Maintenance Mode

There are two maintenance modes for the Model GD-K77D: Maintenance Mode 1 and

Maintenance Mode 2. Under Maintenance Mode 1, you can perform a zero adjustment

and confirm the alarm points. Under Maintenance Mode 2, you can confirm bias voltage

(optional), perform a zero adjustment, perform a span adjustment, and determine a

sensor’s start-up time. See “Calibration” under “Maintenance” for more information about

using Maintenance Mode 2.

To activate Maintenance Mode, remove the Model GD-K77D’s cover, then press and hold

the Mode switch for three (3) seconds.

External output

Gas

Con centration

22mA

20mA

Maintenance mode

6% of full s cale

zero suppression

2. 5 mA

4 mA

Full

Scale

Measuring mode