Appendix A - Electrical Calibration; Equipment Required; Preparation - ABB ZDT Installation And Operating Manual

APPENDIX A – ELECTRICAL CALIBRATION
Note. Electrical calibration is carried out prior to despatch and further calibration should never be necessary. However, if
inaccurate or inconsistent readings are obtained, follow the procedures detailed in this Section.
A.1 Equipment Required
a) Millivolt source (cell input simulator), –20.0 to 180.0mV.
b) Millivolt source (temperature input simulator), 10.0 to 40.0mV.
c) Digital voltmeter (current output), 0 to 20mA.
d) Thermometer, to measure ambient temperature.
A.2 Preparation
a) Switch off the mains supply. Disconnect the probe and retransmission output terminations from the instrument – see Fig. 4.2.
b) Connect the millivolt sources and the milliammeter to the appropriate terminals – see Fig. A.1.
c) With both front panel covers in place, switch on the mains supply to the instrument and allow ten minutes for the circuits
to stabilize.
d) Select the
Electrical Calibration Page
MAINS
E N L
Power
Supply
(110V or
240V a.c.)
22
and proceed as detailed in Section A.3, following.
RELAY RELAY
1 2
RTX
+
N/C C N/O N/C C N/O
88. 8
mA
Retransmission
Output Monitor
(Digital Voltmeter, set to
read milliamps)
Fig. A.1 Electrical Connections – Calibration
Not Used
HEATER
DRIVE CELL
– + –
H H E
SCR
88. 8
mV
Cell Input
Simulator
(–20.0 to 180.0mV
Source)
T/C
+ –
88. 8
mV
Temperature
Input Simulator
(10.0 to 40.0mV
Source)