Gestra LRGS 15-1

Conductivity Switch LRGS 15-1

Data Sheet 818760-01 Issue Date: 07/17
Conductivity Switch
LRGS 15-1
Description
Technical Data
The conductivity switch LRGS 15-1 is a compact system consisting of a conductivity monitoring electrode and a conductivity switch integrated in the terminal box.
The LRGS 15-1 is used as limit switch and continuous blowdown controller in steam boilers.
Temperature coefficient Tk (if a resistance thermo­meter Pt 100 is connected)
1.6 – 3.0 % per °C, adjustable in steps of 0.1
Function
C
The conductivity switch works according to the conductometric measuring method, continuously sensing the electrical
conductivity of the boiler water and thus taking a direct measurement of the total dissolved solids (TDS).
The conductivity switch features an integrated 2-posi­tion controller for actuating a continuous blowdown valve and
automatic closing of the valve on boiler shut-down. Furthermore, an additional adjustable contact outputs a signal when
a limit is reached.
The electrical conductivity being a function of temperature, the measured value must be based on a reference temperature of 25 °C. For calibration purposes a reference
measurement (at 25 °C) is therefore required.
If, however, a resistance thermometer (boiler water temperature) is applied, the adjustable temperature coefficient can
be used to compensate the obtained conductivity values. This means that the conductivity reading will not be affected by
variations in pressure and temperature.
Electrical conductivity is measured in units of micro­Siemens per centimeter (µS/cm). However, in some countries the unit
ppm (parts per million) is used. Conversion: 1 µS/cm = 0.5 ppm. The conductivity switch can be switched to either µS/
cm or ppm.
Technical Data
LRGS 15-1
Service pressure PN25: 25 barg at 224 °C Mechanical connection Screwed ¾", ISO 228-1
Screwed ¾" NPT (optional) Materials Screw-in electrode body:
1.4571, X6CrNiMoTi17-12-2 or 1.4404, A 479 316 L (for NPT thread) Measuring electrode: 1.4571, X6CrNiMoTi17-12-2
Electrode rod insulation: PTFE Terminal box: Polycarbonate Measuring length & length of installation
200, 300, 400, 500, 600, 800, 1000 mm Input 1 Input for resistance thermometer, e. g. TRG 5-53,
measuring insert Pt 100 Measuring range 100 to 10000 µS/cm at 25 °C or 50 to 5000 ppm
at 25 °C Setpoint Adjustable between 100 and 10000 µS/cm or 50 to 5000 ppm
MAX limit Adjustable between 100 and 10000 µS/cm or 50 to 5000 ppm Switching hysteresis
Controller output: –10 % of the adjusted setpoint
MAX limit: –3 % of the adjusted MAX limit
– continued –
Supply voltages 230 V, +10 / –15 %, 50-60 Hz 115 V, +10 / –15 %, 50-60 Hz (optional)
Power consumption 5 VA Fuse External slow-blow fuse 63 mA at 230 V External slow-blow fuse 125 mA at 115 V
Output 3 Volt-free relay contacts 5 A 230 V AC / 30 V DC cos φ = 1 (IEC 61810)
Provide contactor with inference suppressor (RC combination).
Contact material: AgNi 0.15 Indicators and adjustors 1 Four-digit, seven-segment indicator, red, for showing the
actual value (X) / setpoint (W) and status & malfunction messages 2 Amber LEDs for indicating the actual value (X) /
setpoint (W) 1 Red LED for indicating the MAX limit 2 Green LEDs for indicating “Valve OPEN / CLOSED”
4 Pushbuttons for parameter settings Cable entry / Electrical connection
Cable glands with integrated cable clamp, 3 x M 16 x 1.5 1 Four-pole screw-type terminal strip for mains connection
1 Three-pole screw-type terminal strip for connecting the ­continuous blowdown valve
1 Three-pole screw-type terminal strip for MAX limit The terminal strips can be detached;
conductor size 1.5 mm2 4 Terminal lugs for connecting the resistance thermometer
Protection
IP 65 to DIN EN 60529 Protection class 2 (protective insulation) Weight Approx. 1.5 kg
Ambient temperature when system is switched on: 0 ° ... 70 °C, during operation: -10 ... 70 °C
Transport temperature –20 ... +80 °C (< 100 hours), defrosting time of the de-energized equipment before it can be put into operation: 24 hours.
Storage temperature –20 ... +70 °C, defrosting time of the de-energized equipment
before it can be put into operation: 24 hours.
Relative humidity max. 95%, no moisture condensation Site altitude max. 2000 m