GESTRA NRR 2-52, 2-53, URB 50

Level Controller & Display Unit

Description

GESTRA NRR 2-52, NRR 2-53 Level Controller & URB 50 Display Unit

Looking for a reliable and precise boiler water level control system? The GESTRA NRR 2-52, NRR 2-53 Level Controllers, and the URB 50 Display Unit offer a powerful, integrated solution for steam boiler water level monitoring, automation, and safety compliance.

Built with German engineering precision, these devices work seamlessly together to ensure fail-safe operations, accurate level regulation, and real-time monitoring in industrial steam and hot water systems.

Product Highlights

GESTRA NRR 2-52 Level Controller

Designed for use with GESTRA level electrodes (e.g., NRG 26-21, NRG 26-40)
Monitors and controls the minimum water level in steam boilers
Failsafe operation and TÜV-tested for use in safety-related applications
Continuous system self-checks to prevent faults
Outputs: 4-20 mA signal, relay contacts for alarms or pump control

GESTRA NRR 2-53 Level Controller

Provides ON/OFF or modulating control of water level
Works in tandem with NRG series sensors for precision
Supports 2-position and continuous control modes
Enhanced functionality over NRR 2-52 for more complex systems
Used in both single boiler and cascade boiler systems

GESTRA URB 50 Display Unit

Digital display for real-time water level indication
Simple user interface with high-visibility LED indicators
Displays data from GESTRA level electrodes via CANopen or 4-20 mA
Wall or panel mountable, IP65-rated front panel
Alarm and system status visual indicators

Technical Specifications

Feature	NRR 2-52	NRR 2-53	URB 50 Display Unit
Power Supply	24 V DC / 230 V AC	24 V DC / 230 V AC	24 V DC
Control Type	ON/OFF	ON/OFF / Modulating	Display Only
Inputs	1x GESTRA Level Probe	Up to 2x Probes	Analog / CANopen
Output Signal	4-20 mA / Relays	4-20 mA / Relays	Visual Display
Mounting	DIN rail	DIN rail	Panel / Wall Mount
Protection Class	IP20	IP20	IP65 (front panel)

Technical Data

NRR 2-52, NRR 2-53

Supply voltage

24 VDC +/– 20%

Fuse

external 0.5 A (semi-delay)

Power consumption

5 VA

Connection of level electrode / level transmitter (switch-selectable)

1 input for level electrode NRG 21-.. or NRG 26-21, with 3 poles and screen or

1 analogue input 4-20 mA, e. g. for level transmitter NRGT 26-1, with 2 poles and screen

Supply voltage of level electrode

12 VDC

Input/output

Interface for data exchange with operating & display unit URB 50

Inputs

1 analogue input potentiometer 0 – 1000 Ω, two-wire connection (indication of valve position, only NRR 2-52)

1 analogue input 4-20 mA (steam flowrate) (optional)

1 analogue input 4-20 mA (feedwater flowrate) (optional)

Outputs

NRR 2-52: 2 volt-free change-over contacts,

8 A 250 V AC / 30 V DC cos j = 1 (control valve). 2 volt-free change-over contacts,

8 A 250 V AC / 30 V DC cos j = 1,

De-energizing delay: 3 seconds (MIN/MAX alarm).

NRR 2-53: 4 volt-free change-over contacts, 8 A 250 V AC / 30 V DC cos j = 1,

De-energizing delay: 3 seconds (MIN 1, MIN 2 / MAX 1, MAX 2 alarm)

1 analogue output 4-20 mA, max. load 500 ohm (manipulated variable Y).

Provide inductive loads with RC combinations according to manufacturer’s specification to ensure interference suppression

NRR 2-52, NRR 2-53: 1 analogue output 4-20 mA, max. load 500 ohm (e. g. for actual value indication) (optional)

Indicators and adjustors

1 tri-colour LED indicator (start-up = amber, power ON = green, malfunction = red) 1 code switch with four poles for configuration

Housing

Housing material: base: polycarbonate, black; front: polycarbonate, grey Conductor size: 1 x 4,0 mm² solid per wire or

x 5 mm2per stranded wire with sleeve to DIN 46228 or
x 5 mm2per stranded wire with sleeve to DIN 46228 (min. Æ 0.1 mm) terminal strips can be detached separately

Fixing of housing: Mounting clip on supporting rail TH 35, EN 60715

Electrical safety

Pollution degree 2 for installation in control cabinet with protection IP 54, completely insulated

Protection

Housing: IP 40 to EN 60529 Terminal strip: IP 20 to EN 60529

Weight

approx. 0.5 kg

Ambient temperature

when system is switched on: 0° … 55 °C, during operation: –10 … 55°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

Approvals:

TÜV certificate VdTÜV Bulletin “Water Lever 100” (= Water Level 100): Requirements made on water level limiting & control equipment.

Type approval no. TÜV · WR · XX-427 (see name plate).

UL/cUL (CSA) Approval UL 508 and CSA C22.2 No. 14-13, Standards for Industrial

Control Equipment. File E243189.

URB 50

Supply voltage

24 VDC +/– 20%

Fuse

internal automatic

Power consumption

8 VA

Input / output

Interface for data exchange.

User interface

Analogue resistive touch screen, resolution 480 x 271 pixels, illuminated.

Dimensions

Front panel: 147×107 mm Panel cut-out: 136×96 mm Depth: 56 + 4 mm

Electrical connection

1 connector with 3 poles,

D-SUB connector with 9 poles.

Protection

Front panel: IP 65 to EN 60529 Back: IP 20 to EN 60529

Weight

approx. 1.0 kg

Ambient temperature

when system is switched on: 0 ° … 55 °C, during operation: –10 … 55 °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

5 – 85 %, no moisture condensation

Scope of supply

NRR 2-52

1 Level controller NRR 2-52

1 Installation manual

NRR 2-53

1 Level controller NRR 2-53

1 Installation manual

URB 50

1 Operating & display unit URB 50 1 Data line L = 5 m