VEGA VEGACAP 82-98 - Manual (Page 27)

VEGACAP 27
The oscillator is factory-adjusted to the basic
capacitance of the electrode. The relay out-
put switches when the active part of the elec-
trode is covered. Varying dielectric constants
of products, such as e.g. in mixing vessels
have no effect on the switching accuracy
within the active length. The selection of the
electrode length is thus very important since
the length determines the switching point
which cannot be shifted on the electrode
(exception: the electrode of VEGACAP 35
can be shortened).
The electrodes can be fabricated with differ-
ent high-resistance insulating materials and
are thus suitable for corrosive products (see
also "1.2 Types and versions“).
The electrodes VEGACAP 27, 35 and 98 are
also unaffected by buildup.
Exceptions
In rare cases, e.g. in pipelines or when the
electrode is mounted very close to the vessel
wall or where high standing capacitances
exceed the preadjustment of VEGACAP, it
can happen that the electrode signals overfill-
ing (covered) even if the electrode is uncov-
ered. The oscillator of VEGACAP must be
readjusted.
In the following cases, a new adjustment is
necessary:
- in case of electrodes with a length of more
than 3 m
- in case of cramped installation conditions
with high standing capacitance (pipes
etc.),
- in products with a very low dielectric con-
stant
- after shortening of the cable electrode
VEGACAP 35 by more than 0.5 m,
- after exchange of the oscillator.
Setup
New adjustment
• Make sure that the electrode is uncovered.
• Push through the adhesive cover, as on
figure 4.3, with a screwdriver.
• Turn the potentiometer first anticlockwise
until the control lamp signals the condition
„covered“ (max. 20 turns).
- mode A (overfill protection) -
control lamp lights
- mode B (dry run protection) -
control lamp extinguishes
If this condition has already been reached,
continue with the following item.
• Turn the potentiometer very slowly (due to
the integration time) clockwise until the
control lamp signals the condition „uncov-
ered“:
- mode A (overfill protection) -
control lamp extinguishes
- mode B (dry run protection) -
control lamp lights
• Then turn the potentiometer clockwise acc.
to the following table. The instrument is
ready for operation
Sensitivity
Standard very
sensitive
VEGACAP DK
³ 2
DK
³ 1.5
27, 98 2.0 turns 1 turn
VEGACAP DK ³ 1.5
35 2.5 turns
Fig. 4.3