Total Dissolved Solids (TDS) Controllers - SPECTORmodul | Gestra

GESTRA SPECTORmodul – TDS Conductivity Controllers

The LRR 1-50 / LRR 1-51 controllers are designed for continuous monitoring of boiler water conductivity and automated blowdown valve actuation. Conductivity is used as an indirect measurement of Total Dissolved Solids (TDS); as TDS increases, the controller opens the blowdown valve until the setpoint is reached, factoring in the configured hysteresis.

Variants

• LRR 1-50: Direct connection to conductivity electrodes LRG 12-2, LRG 16-4, LRG 16-9, LRG 17-1, LRG 19-1.
• LRR 1-51: For use with transmitters LRGT 16-1, 16-2, 16-3, 16-4, 17-1, 17-3 providing a 4–20 mA signal.
• LRS 1-50: Conductivity MIN/MAX switch for limit monitoring where full valve control is not required.

Control Operation

The LRR operates as a 2-position controller. At the conductivity threshold, it actuates the blowdown valve to OPEN. Once conductivity drops below the hysteresis band, the valve returns to OPERATING. Valve closure is enforced during boiler shutdown to prevent water loss.

Technical Data

• Power supply: 24 VDC ±20%
• Power consumption: 4 W
• Outputs: Contacts for OPEN / OPERATING / CLOSED
• Alarm: MAX contact
• Analog output: 4–20 mA (actual or manipulated value)
• Display: 4-digit 7-segment LED
• Mounting: DIN rail TH 35 (EN 60715)
• Protection: IP40 housing, IP20 terminals, IP65 with panel adaptor

Measuring Range

LRR 1-50: 1–10,000 μS/cm at 25°C or 1–5,000 ppm. LRR 1-51: accepts 4–20 mA from LRGT, adjustable up to 12,000 μS/cm, display up to 9999 μS/cm.

Installation Notes

Use shielded cable, segregate from power wiring, and provide external 0.5 A fuse on supply. For limiter applications, latching is not internal; interlock must be implemented in the downstream safety circuit per EN 50156.

Applications & Media

• Steam and hot water boiler TDS control
• Suitable for boiler water, condensate, and process water
• Compliant with industrial safety and control standards