Issue 6 – December 2006
25
Calibrating an SE Ex unit
Use the controls on the pellistor board to set sensor current, calibrate zero and
calibrate span:
(Also refer to the measuring head’s operating manual for calibration instructions.)
Set the sensor current
1. Set the sensor drive current range with SW1-A on the pellistor board.
For all Dräger sensors, set SW1-A to
OFF
.
SW1
Drive current
range
A
B
C
D
95 – 195 mA
ON
–
–
–
190 – 350 mA
OFF
– – –
The position of switches B, C and D does not matter yet.
2. Adjust the sensor current to the required value
x
Turn off the unit by disconnecting the AC or DC supply and batteries, if fitted
x
Connect an ammeter between terminal 9 and the sensor
x
Re-connect the AC or DC supply
x
Adjust VR2 on the pellistor board to set the current (270.0 mA for Dräger Ex
sensors). Allow two minutes for the current to settle after adjusting VR2. Re-
adjust VR2 if necessary
x
Disconnect power, remove the ammeter and reconnect the sensor
x
Turn on power and allow sensor to settle or at least five minutes before
continuing with zero and calibration
SW1
VR3
VR1
VR2
Summary of Contents for REGARD-1
Page 38: ...Issue 6 December 2006 38 EC type examination certificate ...
Page 39: ...Issue 6 December 2006 39 ...
Page 40: ...Issue 6 December 2006 40 ...
Page 41: ...Issue 6 December 2006 41 ...
Page 44: ...Issue 6 December 2006 44 ...
Page 46: ...Issue 6 December 2006 46 ...
Page 47: ...Issue 6 December 2006 47 ...