GESTRA SPECTORmodul – Boiler Level Controllers
The GESTRA SPECTORmodul level controllers are designed for use in steam boilers, pressurized hot water systems, condensate tanks, and feedwater tanks. They interface with level electrodes NRG 21 / NRG 26-21 or transmitter NRGT 26, converting the signal to a 0–100% indication of the boiler’s measuring range.
Control Versions
- NRR 2-50: Three-position PI controller for electric valve actuators. Provides open/close commands via two relay contacts.
- NRR 2-51: Continuous PI controller for electro-pneumatic valves, with 4–20 mA control output.
- NRS 2-50: Level switch for MIN/MAX alarm signaling.
- NRS 2-51: Level switch with additional on/off control for feedwater pumps.
Process Operation
The controller compares actual level to setpoint and actuates the feed or discharge valve, depending on fill or discharge control configuration. Upon reaching MIN or MAX limits, an alarm relay is triggered after a 3 s dropout delay. Electrode, transmitter, wiring, or configuration faults are indicated as error codes on the 7-segment display.
Electrical Data
- Supply: 24 VDC ±20%
- Protection: external fuse 0.5 A
- Power consumption: 2 W (NRR), 4 W (NRS)
- Output contacts: 8 A, 250 VAC / 30 VDC
- Analog output: 4–20 mA, max load 500 Ω
- Mounting: DIN rail TH 35, EN 60715
- Enclosure: IP40 housing, IP20 terminals, IP65 with panel adaptor
Selection Criteria
Selection depends on sensor type, valve actuation method, analog output requirements, MIN/MAX alarm logic, and pump or valve control logic. Not suitable for use in explosive atmospheres.
Typical Applications and Use Cases
- Steam and hot water boiler level control
- Feedwater tank monitoring
- Condensate tank level management
- Integration with electric or pneumatic actuators
- Alarm signaling for process safety
Compatible with water and steam media. Designed for industrial environments requiring compliance with EN 60715 and relevant electrical safety standards.