Metrohm 773 pH/mV Simulator - Manual (Page 10)

2.6. Checking the polarization source
773 pH/mV Simulator
8
2.6 Checking the polarization source
For microprocessor-controlled instruments it is better to check the
polarization source with the aid of the instrument diagnosis; please
refer to the ‘Instructions for Use’ of the instrument or titrator. The ca-
ble connections are shown below.
773 pH/mV Simulator
x100
x10
x1
-
-
14,3k PT1000 PT100 RE WE WE ON/OFF
pH U/mV
- +
20
6
4
2 18
16
14
12
10
8
0
+ +
0
20 25 40 60 80
100 C
1000
~0,002
pH=7
U=0mV
i R /M
If no diagnosis instructions are available please proceed as follows:
1. Connect the sockets "14.3 k
Ω " of the 773 pH/mV Simulator with
the Pol measuring input of the instrument being checked with
6.2150.050 Cable.
For instruments with banana plugs (e.g. 692) use 6.2150.000 Cables.
2. Set the instrument being checked to measurement with polarized
electrodes (Ipol).
3. The measured value depends on the polarization current and is
calculated as follows:
U = R x I = 14.3 k
Ω x set polarization current
Example with Ipol = 1 uA:
Measured value U = 14.3 k
Ω X 1 uA = 14.3 mV
The polarization potential source Upol can be checked similarly. The measured
value is calculated from
I = U/R
The exact values for the resistances can be found in the table on the
upper side of the instrument (field R-Test / R). Please take into ac-
count both the resolution of your instrument’s display and the infor-
mation about tolerances given in the ‘Instructions for Use’ for your
instrument. With low values for the polarization current or potential
the variations may be slightly higher.
6.2150.050 Cable