Vega VEGACAP 27 Operating Instructions Manual page 15

Switching point adapta-
tion (6)
Mode adjustment (5)
Signal lamp (4)
Switching point adjust-
ment
Exceptions
Fresh adjustment
VEGACAP 27 • Relay (DPDT)
To adjust VEGACAP 27, loosen first of all the four screws on the up-
per side of the instrument with a screwdriver and remove the housing
cover.
You can adapt the switching point to the solid with the potentiometer.
The electronics is adjustment free and an adaption is only necessry in
exceptions. See " Exceptions".
With the mode switch you can change the switching condition of the
relay. You can set the required mode (A - max. detection or overfill
protection, B - min. detection or dry run protection).
We recommend connecting according to the idle current principle
(relay contact deenergizes when the switching point is reached),
because the relay always takes on the same (safe) state if a failure is
detected or in case of mains failure.
Control lamp for indication of the switching status
•
Control lamp on = Relay deenergised
The measuring system is immediately ready for operation.
The switching point must no longer be set with VEGACAP 27.
The probe has an active tip and a screen segment. Thanks to the
screen segment, the so called standing capacitance, caused by the
vessel after installation of the probe, is mainly compensated.
As a default setting, the electronics module is adjusted to the basic
capacitance of the probe. The relay output switching when the active
tip is covered (active tip: 50 ... 150 mm / 2 ... 5.9 in) of the electrode.
Changing dielectric values of the products, such as e.g. caused in
mixing vessels are no problem for the switching accuracy within the
active pin. The selection of the electrode length is hence very impor-
tant because the length of the electrode determines the switching
point. This switching point cannot be shifted on the electrode.
In exceptions, e.g. in pipelines or if the probe is mounted very close to
the vessel wall, it can happen ath the probe signals already overfilling
(covering) in uncovered condition.
In this case, the switching point must be re-adjusted.
For adjustment, the vessel must not be filled and the switching point
adjustment is also possible in dismounted condition.
A fresh adjustment is necessary in the following cases:
•
for probes with a length of more than 3 m (9.8 ft)
•
in narrow space installation conditions with high standing capaci-
tance (e.g. in tubes etc.)
•
after exchange of the electronics module
Proceed as follows for a fresh adjustment:
1. Make sure that the probe is uncovered.
2. Pierce the cover of the potentiometer (6) with a screwdriver.
6 Setup
15