Single and Dual Input Analyzers for Low Level Conductivity
AX410, AX411, AX413, AX416, AX418, AX450, AX455 & AX456
7 CALIBRATION
IM/AX4CO Issue 11
61
7 CALIBRATION
7.1 Equipment Required
1. Decade resistance box (conductivity cell input simulator): 0 to 10k
Ω
(in increments of 0.1
Ω
), accuracy ±0.1%.
2. Decade resistance box (Pt100/Pt1000 temperature input simulator): 0 to 1k
Ω
(in increments of 0.01
Ω
), accuracy ±0.1%.
3. Digital milliammeter (current output measurement): 0 to 20mA.
7.2 Preparation
1. Switch off the supply and disconnect the conductivity cell(s), temperature compensator(s) and current output(s) from the
analyzer's terminal blocks.
Sensor A - Fig. 7.1:
a. Link terminals B9 and B10.
b. Connect one terminal of the 0 to 10k
Ω
decade resistance box to B13 and the other terminal to B14 to simulate the
conductivity cell. Connect the decade resistance box earth to B12.
c. Connect one terminal of the 0 to 1k
Ω
decade resistance box to B9 and the other terminal to B11 to simulate the
Pt100/Pt1000.
Sensor B (dual input analyzers only) - Fig. 7.1:
a. Link terminals B1 and B2.
b. Connect one terminal of the 0 to 10k
Ω
decade resistance box to B5 and the other terminal to B6 to simulate the
conductivity cell. Connect the decade box resistance earth to B4.
c. Connect one terminal of the 0 to 1k
Ω
decade resistance box to B1 and the other terminal to B3 to simulate the
Pt100/Pt1000.
3. Connect the milliammeter to the analog output terminals.
4. Switch on the supply and allow ten minutes for the circuits to stabilize.
5. Select the
FACTORY SETTINGS
page and carry out Section 7.3.
Note.
The analyzer is calibrated by the Company prior to dispatch and the Factory Settings pages are protected by an access
code.
Routine recalibration is not necessary - high stability components are used in the analyzer's input circuitry and, once
calibrated, the Analog-to-Digital converter chip self-compensates for zero and span drift. It is therefore unlikely that the
calibration will change over time.
Do Not attempt recalibration without first contacting ABB.
Do Not attempt recalibration unless the input board has been replaced or the Factory Calibration tampered with.
Prior to attempting recalibration, test the analyzer's accuracy using suitably calibrated test equipment - see section 7.1,
page 61 and see section 7.2, page 61.
Note.
Resistance boxes have an inherent residual resistance that may range from a few m
Ω
up to 1
Ω
. This value must be taken
into account when simulating input levels, as should the overall tolerance of the resistors within the boxes.
