Service and Maintenance -
Check with Test Gas
65
Once adjustment has been triggered, air is blown through the protective pipe to the
sampling point. The gas quantity is set automatically via the calibration pump in such a
way that the pre-filter is pressurized at between 2...5 mbar. This prevents flue gases
from reaching the sampling point in the protective pipe, thereby ensuring that only
adjustment gas is present at the measuring gas sampling point.
The pressure in the filter is measured by means of an absolute pressure sensor and
the measured value is compensated within defined limits (± 50 mbar). If the filter
becomes contaminated, the gas flow is reduced via the proportional valve. If the flow
rate is too low while the pressure is increasing quickly, the alarm "sintered metal pre-
filter is contaminated" is output.
Due to its size, the filter is relatively resistant to contamination. If only a small part of
the surface remains clean, this is sufficient for the measuring gas quantity of approx.
0.5 l/h required for the measurement.
Each calibration is registered into calibration history (Par.1570... 1791). The calibration
history can be reseted via par.119.
7.3
Check with Test Gas
A check can be triggered as follows:
•
Display/control unit (optional)
•
Via the PC in conjunction with the remote display software (optional)
NOTE
The calibration is protected with a password. Which release level is to be used , can
be set in par.260:
OFF
Æ
No password is necessary
CUSTOMER
Æ
Customer’s password is necessary (factory setting)
SERVICE
Æ
Service password is necessary
MAINTENANCE
Æ
Maintenance mode is necessary
CU MAINTENANCE
Æ
Customer’s pw + Maintenance mode is necessary
S MAINTENANCE
Æ
Service pa Maintenance mode is necessary
NOTE
The measuring gases used must not contain any combustible gas constituents (e.g.
carbon monoxide (CO)). Combustible gas constituents are oxidized (incinerated) on
the platinum electrode of the zirconium dioxide measuring cell, which is approx. 800
°C, and reduce the oxygen to be measured.
NOTE
The manual calibration is limited according to factory setting on 15 min. At expiration
of this time the equipment shifts back automatically into the measuring mode.
