VEGA Capacitive electrodes User Manual
Operating Instruction
Capacitive electrodes EK …
with signal conditioning instrument
Level and Pressure
Safety information
Safety information
The described module must only be installed
and operated as described in this operating
instruction. Please note that other action can
cause damage for which VEGA does not take
responsibility.
2 Capacitive electrodes EK with signal conditioning instrument
Note Ex-area
Please note the attached approval documents
(yellow binder) and especially the included
safety data sheet.
Contents
Contents
Safety information ........................................................................ 2
Note Ex-area ................................................................................ 2
1 Product description
1.1 Function and configuration .................................................. 4
1.2 Types and versions ............................................................. 6
1.3 Technical data ....................................................................... 8
1.4 Approvals ........................................................................... 14
1.5 Dimensions ......................................................................... 15
1.6 Type plate ........................................................................... 17
2 Mounting
2.1 Mounting instructions ......................................................... 18
3 Electrical connection
3.1 Connection instructions ..................................................... 23
3.2 Wiring plan .......................................................................... 24
4 Set-up
4.1 General adjustment ........................................................... 27
4.2 Level detection ................................................................... 28
4.3 Continuous level measurement ......................................... 29
5 Diagnosis
5.1 Simulation ............................................................................ 31
5.2 Maintenance ....................................................................... 31
5.3 Repair .................................................................................. 31
5.4 Failure removal ................................................................... 32
Capacitive electrodes EK with signal conditioning instrument 3
1 Product description
1.1 Function and configuration
Capacitive electrodes series EK detect levels
of virtually any medium, unaffected whether
liquids, powders, granules or pastes. This is
also valid for adhesive mediums.
The electrode measures also the level capacitance and the ohmic resistance (admittance processing). Hence also problematic
mediums and solids with fluctuating humidity
contents can be detected.
By the use of screening tubes and screen
segments, inactive areas can be provided on
the probe where pollution, condensation or
permanent build-up do not influence the
measuring result.
Measuring principle
Electrode, medium and vessel wall form an
electrical capacitor.
Product description
Electrode and vessel wall are the capacitor
plates. The medium is the dielectricum. Due
to the higher dielectric constant figure (DKvalue) of the medium against air, the capacitance of the capacitor increases with raising
covering of the electrode.
Fig. 1.2 Capacitance change with covered
electrode
The capacitance of the capacitor is mainly
influenced by three factors:
- distance of the electrode plates (a)
- size of the electrode plates (b)
The capacitance change is converted by the
oscillator into a level proportional, floating
current in the range of 4 … 20 mA or into a
switching command.
- kind of dielectricum between the electrodes (c)
Continuous level measurement
With the continuous level measurement, the
appropriate level is continuously detected
and converted into a level proportional signal
which is either directly indicated or further
b
c
Fig. 1.1 Plate capacitor (schematic demonstration)
4 Capacitive electrodes EK with signal conditioning instrument
processed.
You require a capacitive electrode series EK
with oscillator and a signal conditioning instrument VEGAMET, converting the proportional current of the oscillator into
standardised current and voltage signals.
The continuous measurement requires a
constant dielectric constant figure er, i.e. if
possible the medium should have steady
features.
Product description
The floating signal of the electrode electronics
is in the range 4 … 20 mA and can be therefore connected without additional potential
separation to other processing systems such
as e.g. VEGALOG.
In addition to the continuous measurement,
also levels can be detected (VEGAMET or
VEGAMET + VEGASEL).
Level detection
Level switches should signal when certain
levels are reached, e.g. max. or min. levels.
These levels are detected at a fixed point
and converted into a switching command.
For level detection capacitive electrodes EK
with appropriate signal conditioning instruments VEGATOR are available. A switching
command can be either triggered when the
electrode is covered or uncovered.
Capacitive electrodes EK with signal conditioning instrument 5
Product description
1.2 Types and versions
*)
Type
Version 11 21 24 26 31 42
Continuous • • • • •
Level detection • • • • • •
Partly insulated • •
Fully insulated • • • •
Oscillators
E 14 • • • •
E 15 • • • •
E 15 Ex • • • •
E 17 • • • •
E 17 Ex • • • •
E 18 ••••••
E 18 Ex • • • • • •
Approvals
CENELEC EEx ia IIC T6 • • • • • •
PTB-Zone 0 EEx ia IIC T6 • • • • • •
Overfill protection
acc. to WHG • • • • • •
German Lloyd
Lloyds Register of Shipping
American Bureau of Shipping
Bureau Veritas
RINA
1)
1)
1)
1)
1)
EK EK EK EK EK EK
• •••••
• •••••
• •••••
• •••••
• •••••
Mechanical connection
G 3/4 A • •••••
G 1 A • • • • • •
3/4" NPT • • • • • •
1“ NPT • • • • • •
Flange plated • •
Electrode material
Steel • •
StSt •
Isolating material
5)
2)
2)
•
3)
•
4)
•
3)
•
PTFE • • • •
FEP • •
PE • • •
6 Capacitive electrodes EK with signal conditioning instrument
Product description
*)
Version 11 21 24 26 31 42
Type
Concentric tube
StSt • •
Screening tube (option)
StSt • • • • •
Temperature adapter
(option)
StSt • • • •
Housing material
Plastic (IP 66) • • • • • •
Aluminium - plastic coated
(IP 66 and 67) • • • • • •
Others
Bending of
electrode
6)
*) All instrument types also Ex0
1) applied
2) 1.4435
3) 1.4571
4) 1.4401
5) For electrodes certified for Ex-Zone 0, only PTFE and FEP are approved as isolating material.
6) Bending max. 90°
7) EK 21 only with PTFE with 3,2 mm isolation thickness
EK EK EK EK EK EK
••
7)
Capacitive electrodes EK with signal conditioning instrument 7
Product description
1.3 Technical data
Housing
Housing material plastic PBT (Polyester) or Aluminium
Protection
- plastic housing IP 66
- Aluminium housing IP 66 and 67 (meets both protections)
Cable entry 1 pce. M20 x 1,5
Terminals for max. 1,5 mm2 cross-section area of
Mechanical connection
Material 1.4435 (316 L)
Thread G 3/4 A or 3/4“ NPT
Flange flange versions, plated
Electrode
Material EK 11 1.4435 (316 L)
Length
- rod max. 3 m
- cable max. 20 m
Isolation see "Isolating materials"
Max. tensile strength
- EK 31 3 KN
- EK 42 3 KN
plastic coated
conductor
G 1 A or 1“ NPT
EK 21 steel (St 37), 1.4435 (316 L)
EK 31 1.4401 (316 L)
EK 24, 42 1.4571 (316 L)
Ambient conditions
Ambient temperature on the housing -40°C … +80°C
Medium temperature see "Product temperature and operating
Storage and transport temperature -40°C … +80°C
Operating pressure see "Product temperature and operating
Oscillators E14, E15, E17, E18
Protection class II
Overvoltage category III
Meas. frequency see table on the following page
Capacitance ranges see table on the following page
Supply voltage 12 … 36 V DC (powered by signal conditioning
Potential separation min. 500 V DC (except E14)
8 Capacitive electrodes EK with signal conditioning instrument
pressure"
pressure"
instrument)
Product description
For Ex-applications note the permissible
electrical connection values stated in the
certificate.
Load in W
Accessory
Straining spring of 1.4571 (EK 42, EK 52, EK 53)
- load approx. 185 mm (stressed)
- tensile load approx. 200 N
Weight
Basic weight (e.g. EK 24) approx. 0,8 kg
Rod weight ø 6 mm - 0,23 kg/m
ø 10 mm - 0,62 kg/m
Cable weight (EK 31) approx. 40 g/m
Supply
voltage in V
Capacitive electrodes EK with signal conditioning instrument 9
Product description
Oscillators in two-wire technology for capacitive electrodes EK
Typ e Application Meas. range Frequency Signal cond.instr.
E14 Level detection in general I: 0 … 25 pF 400 kHz VEGATOR
E15 Level detection in general I: 0 … 25 pF 400 kHz VEGATOR
with potential separation II: 0 … 100 pF VEGALOG
E15 Ex as E15, however for use in I: 0 … 25 pF 400 kHz VEGATOR Ex
hazardous areas acc. to II: 0 … 100 pF VEGALOG
CENELEC, PTB zone 0 as well as III: 0 … 400 pF
zone 1 and StEx zone 10 and as
part of an overfill protection acc. to
WHG, (VbF)
E17 Continuous level measurement in I: 0 … 120 pF 40 kHz VEGAMET
general or level detection with II: 0 … 600 pF VEGALOG
potential separation III: 0 … 3000 pF (VEGATOR)
E17 Ex as E17, however for use in I: 0 … 120 pF 40 kHz VEGAMET Ex
hazardous areas acc. to II: 0 … 600 pF VEGALOG
CENELEC, PTB zone 0 as well as III: 0 … 3000 pF (VEGATOR Ex)
zone 1 and StEx zone 10 and as
part of an overfill protection acc. to
WHG, (VbF)
2)
E18
Continuous level measurement I: 0 … 120 pF 470 kHz VEGAMET
or level detection with potential II: 0 … 600 pF VEGALOG
separation acc. to the principle of III: 0 … 3000 pF (VEGATOR)
phase selective admittance processing especially for adhesive mediums
and for the use in solids with
varying humidity
2)
E18 Ex
as E18, however for the use in I: 0 … 120 pF 470 kHz VEGAMET Ex
hazardous areas acc. to II: 0 … 600 pF VEGALOG
CENELEC, PTB zone 0 as well as III: 0 … 3000 pF (VEGATOR Ex)
zone 1 and StEx zone 10 and as
part of an overfill protection acc. to
WHG, (VbF)
1)
with safety barrier
2)
see following page
II: 0 … 100 pF VEGALOG
III: 0 … 400 pF
III: 0 … 400 pF
1)
1)
1)
10 Capacitive electrodes EK with signal conditioning instrument
Product description
Oscillator E18
The oscillator E18 with the patented processing (phase selective admittance processing)
extends the application range of capacitive
level measurement technology.
In conjunction with the fully insulated rod
electrode EK 24 the oscillator E18 compensates even very conductive build-up.
Mounted in an individual rod or cable electrode type EK, E18 ensures also the exact
measurement in solids with varying humidity
contents.
The oscillator E18 processes the measuring
currents according to their phase position.
Measuring current with a defined phase
shifting as they occur with build-up or humidity changes are filtered out.
Humidity change
A humidity change in solids causes a change
of the dielectric constant figure (er). In parallel
the ohmic value of the medium changes. Due
to the change also a phase shifting of the
measuring currents is caused.
Level
measured value
+
1)
–
0 %
5 %
10 %
1) Actual value level
Fig. 1.3 Humidity change
15 % vol.
fully insulated
electrode
Solid
humidity (%)
partly insulated electrode
With a capacitive measurement already lowest humidity changes cause measuring errors. Typical products are e.g. sand,
aggregate in the cement industry, hop or
plastic granules (after drying).
When using the oscillator E18 humidity
changes of 15 % vol. do not influence the
accuracy of the measurement. Even layering
of product with different humidity does not
play a role for the measuring accuracy.
When the humidity contents exceeds 15 %
vol., fully and partly insulated electrodes
react differently (see also "Fig. 1.3 Humidity
change“). Whereby the measured value on
fully insulated electrodes raises with steady
level, the measured value on partly insulated
electrodes drops.
Capacitive electrodes EK with signal conditioning instrument 11
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