Scope of supply................................................................................................................................................4
System description ..........................................................................................................................................4
Set code switch ..............................................................................................................................................12
Functional test ................................................................................................................................................13
LED display and fault indication...................................................................................................................14
Use conductivity transmitter system LRGT 16-1 only for monitoring electrical conductivity
in liquids.
The equipment has to be supplied with 24 V DC from a safety power supply unit (PSU) in
accordance with DIN VDE 0106 (safe supply isolation). The PSU must be equipped with
an overcurrent protective device according to DIN EN 61010-1/VDE 0411.
The transmitter system LRGT 16-1 must only be installed by qualified staff.
Qualified staff are those persons who - through adequate training in electrical engineering,
the use and application of safety equipment in accordance with regulations concerning
electrical safety systems, and first aid & accident prevention have achieved a recognised
level of competence appropriate to the installation and commissioning of this critical safety
device.
Danger
When loosening the conductivity transmitter system steam or hot water might escape. This
presents the danger of scalding. It is therefore essential not to dismantle the conductivity
transmitter system unless the boiler pressure is verified to be zero.
Explanatory Notes
Scope of Supply
LRGT 16-1
1 Control electrode with joint ring D 33 x 39 DIN 7603-1.4301 E8P
1 Terminal box with conductivity transmitter
1 Installation manual
System Description
The LRGT 16-1 is a compact-design conductivity transmitter system consisting of a
conductivity electrode, a temperature sensor for detecting the fluid temperature and an
integrated conductivity transmitter. The equipment works according to the conductivity
measurement two-electrode control principle and provides a conductivity-dependent and
temperature compensated measuring current of 4 - 20 mA.
The conductivity transmitter system is designed to measure the electrical conductivity in
conductive fluids.
If the LRGT 16-1 is connected to the industrial controller type KS 90 the equipment can be
used as conductivity limiter and/or continuous blowdown controller in steam boilers,
(pressurised) hot-water boilers and condensate systems.
Type Approvals
TÜV WÜL · 01-003
EG BAF-MUC 01 04 105620 001
4
Function
A measuring current of variable frequency flows through the fluid and creates a potential
gradient between the measuring electrode and the measuring tube. The potential gradient
is evaluated as measuring voltage U
.
U
In order to compensate for polarisation, which would reduce the measuring current, the
measuring frequency is adapted accordingly. The resulting measuring current is sensed
and transmitted as measuring voltage U
.
I
The electrical conductivity changes as a function of temperature. The resistance
thermometer integrated in the electrode measures the fluid temperature and establishes a
reference temperature on which the measured values will be based.
The electrical conductivity is calculated from the measuring voltages UU and UI and depending on the adjusted temperature coefficient Tk - is based linearly on the reference
temperature 25 °C. After converting it into a conductivity-proportional current signal, a
current of 4 - 20 mA is provided for external processing.
The cables leading to the measuring electrode, the measuring tube and the resistance
thermometer are monitored for interruption and short circuits. In addition, the electronic
insert is protected against excessive temperatures in the terminal box. In case of a
malfunction the LEDs are permanently illuminated or flashing and the current signal is set
to 0 or 0.5 mA.
The transmitter is parameterised via code switch. The code switch can also be used for
adaptation of the cell constant and triggering a functional test.
The electrical conductivity is measured in µS/cm. In some countries use is also made of
ppm (parts per million). Conversion: 1 µS/cm = 0.5 ppm.
Installation
The conductivity transmitter system is designed such that it can be screwed directly into
boiler standpipes or suitably tapped flanges.
The electrode must be installed such that it is always submerged.
The installation in protection tubes is not permitted according to WÜ 100.
Ensure a minimum distance of approx. 20 mm between the lower part of the measuring
tube and the boiler wall, the smoke tubes, any other metal parts and the low water level
(LW).
Installation of the Measuring Electrode
1. Check seating surfaces of threads or flange provided on vessel or boiler standpipe.
2. Place ring joint onto the seating surface of the transmitter. Note: Use only ring joint (of
stainless steel 1.4301 E8P) D 33 x 39 to DIN 7603 supplied with the electrode.
3. Apply a light smear of silicone grease (e. g. DOW Corning 111 Compound) to electrode
thread.
4. Screw conductivity transmitter electrode into threads or flange provided on vessel or
boiler standpipe and tighten with a 41 mm open-end spanner. The torque required
when cold is 150 Nm. The tapped hole must conform to DIN 3852 part 2, 1" BSP (DIN
ISO 228) form X or Y, standard version. The subsequent hole must have a diameter of
> 24 mm.
5
Reducing length of installation and measuring length (control range)
The measuring tube and the electrode can be cut to suit the individual requirements of the
installation.
4. Loosen fixing nut with 18 (19) mm open-end spanner and remove it.
5. Pull electrode cables through fixing nut.
6. Remove terminal box. Pull all electrode cables through hole for fixing screw.
Install terminal box
1. Pull all electrode cables through hole for fixing screw in terminal box.
2. Place terminal box onto electrode and turn it into the desired direction, taking the cable
outlet into consideration. Ensure correct seat of the gasket between the electrode and
the terminal box.
3. Pull all electrode cables through fixing nut. Screw nut on fixing bolt and tighten with a
torque of 30 Nm.
4. Connect electrode cables according to wiring diagram to terminal lugs (electronic
insert, functional earthing).
5. Screw back cover plate. Install terminal cover and tighten cover screws, ensuring
correct seat of cover gasket.
8
Wiring
Connect conductivity transmitter
The equipment has to be supplied with 24 V DC from a safety power supply unit (PSU) in
accordance with DIN VDE 0106 (safe supply isolation). The PSU must be equipped with
an overcurrent protective device according to DIN EN 61010-1/VDE 0411.
The following steps 1 - 5 do not apply for equipment fitted with a connector.
For wiring use flexible screened control cable, min. conductor size 0.75 mm².
1. Remove terminal strip and pull connecting cable through cable gland.
2. Strip off approx. 40 mm of cable insulation coating and remove approx. 5 mm of
conductor end insulation.
3. Carry out wiring in accordance with wiring diagram.
4. Plug in terminal strip.
5. Seal cable entry by tightening cable glands. Use sealing plug to seal off cable glands
that are not used.
6. Install terminal cover and tighten cover screws, ensuring correct seat of cover gasket.
Tools
! Screwdriver size 1 for cross-recess head screws
! Screwdriver size 2.5 for slotted screws, completely insulated to VDE 0680
! 18 (19) mm open-end spanner
9
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