GESTRA NRR 2-50 User manual

Original Installation &
Operating Manual
850699-00
Level Controller
NRR 2-50
NRR 2-51
EN (USA)
English

2NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Contents
Content of this Manual......................................................................................................................... 4
Scope of supply, product package....................................................................................................... 4
How to use this Manual........................................................................................................................ 5
Illustrations and symbols used............................................................................................................ 5
Hazard symbols in this Manual............................................................................................................ 5
Types of warning .................................................................................................................................. 6
Specialist terms, abbreviations ........................................................................................................... 7
Usage for the intended purpose........................................................................................................... 8
Applicable directives and standards.............................................................................................. 8
Improper use ........................................................................................................................................ 8
Basic safety information ...................................................................................................................... 9
Required personnel qualifications..................................................................................................... 10
Notes on product liability................................................................................................................... 10
Function .............................................................................................................................................. 11
Technical data .................................................................................................................................... 12
Rating plate, identification................................................................................................................. 14
Factory default settings ..................................................................................................................... 15
Changing the factory default settings ............................................................................................... 16
Dimensions of the NRR 2-50, 2-51..................................................................................................... 18
Preparing for installation ................................................................................................................... 19
Installation.......................................................................................................................................... 20
Installing in the control cabinet ...................................................................................................... 20
In the control cabinet: Electrically connecting the level controller.................................................. 21
Wiring diagram for level controller NRR 2-50 ................................................................................. 21
Wiring diagram for level controller NRR 2-51 ................................................................................. 22
Connecting the supply voltage ....................................................................................................... 23
Connecting the output contacts...................................................................................................... 23
Connecting the level transmitter .................................................................................................... 23
Output of manipulated variable Y or connection of actual value output (optional)............................ 23
In the plant: Electrically connecting the level transmitter................................................................ 24
Connecting the level transmitter .................................................................................................... 24

3NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Contents
Operating the level controller ............................................................................................................ 24
Meaning of codes on the 7-segment display.................................................................................. 25
Setting the measuring range (on the NRGT 26-2) ........................................................................... 26
Guide to setting control parameters ............................................................................................... 26
Bringing into service .......................................................................................................................... 27
Setting parameters ........................................................................................................................ 27
Operation, alarm and test................................................................................................................... 28
Setting switchpoints and control parameters ................................................................................. 28
Level controller NRR 2-50 indications ............................................................................................ 29
Level controller NRR 2-51 indications ............................................................................................ 29
Checking the function of the MIN/MAX output contacts .................................................................. 30
Fault indications and troubleshooting............................................................................................... 31
Indications, diagnosis and corrective action ................................................................................... 31
Important notes .................................................................................................................................. 31
Action against high-frequency interference.................................................................................... 31
Taking out of service.......................................................................................................................... 32
Disposal .............................................................................................................................................. 32
UL components................................................................................................................................... 32

4NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Content of this Manual
Product:
■ Level Controller NRR 2-50, NRR 2-51
First edition:
BAN 850699-00/08-2021cm
© Copyright
All rights reserved. Any misuse, particularly reproduction and dissemination to third parties, is not
permitted. The General Terms & Conditions of GESTRA AG apply.
Scope of supply, product package
NRR 2-50
1 level controller NRR 2-50
1 Installation & Operating Manual
NRR 2-51
1 level controller NRR 2-51
1 Installation & Operating Manual

5NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
How to use this Manual
This Installation & Operating Manual describes the correct use of the NRR 2-50, NRR 2-51 level
controller. It applies to persons who integrate this equipment in control systems, install, bring into
service, operate, maintain and dispose of this equipment. Anyone carrying out the above-men-
tioned activities must have read this Installation & Operating Manual and understood its contents.
■ Read this Manual in full and follow all instructions.
■ Please also read the instructions for use of any accessories.
■ The Installation & Operating Manual is part of the product package. Keep it in an easily acces-
sible location.
Availability of this Installation & Operating Manual
■ Make sure this Installation & Operating Manual is always available to the operator.
■ If you pass on or sell the equipment to a third party, please also hand over the Installation &
Operating Manual.
Hazard symbols in this Manual
Danger zone, dangerous situation
Illustrations and symbols used
1. Action to be taken
2.
■ Lists
◆ Bullet points in lists
A Keys to illustrations
Additional
information
Read the relevant
Installation & Operating Manual

6NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Types of warning
DANGER
Warning of a dangerous situation that results in death or serious injury.
WARNING
Warning of a dangerous situation that may possibly result in death or serious injury.
CAUTION
Warning of a situation that may result in minor or moderate injury.
ATTENTION
Warning of a situation that results in damage to property or the environment.

7NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Specialist terms, abbreviations
Here, we explain some abbreviations, specialist terms, etc., which are used in this Manual.
NRGT .. / NRR.. / NRS.. / URS .. / URB .. / SRL .. / etc.
Equipment and type designations of GESTRA AG.
SELV
Safety Extra Low Voltage
Operating point (of the plant)
The operating point describes the operating parameters within which a plant or boiler is operated
in its nominal range. In a steam boiler, for example, these parameters would be output, pressure,
and temperature.
The design data may be a lot more stringent, however.
A boiler that is operated at 145psi (10bar) and 356°F (180°C) may be designed to withstand a
pressure of 870psi (60bar) and a temperature of 527°F (275°C), for example, which is therefore
not necessarily its operating point.

8NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Usage for the intended purpose
The NRR 2-50, NRR 2-51 level controller is used in combination with the NRGT 26-2 level trans-
mitter as a limit switch and water level controller, e.g., in steam boilers and hot water installa-
tions or in condensate and feedwater tanks. The level controller indicates when a MIN and MAX
water level has been reached, and opens or closes a control valve.
The NRR 2-50 and NRR 2-51 are classified as operating controls in accordance with UL60730-1.
When used as intended, the NRR 2-50, NRR 2-51 level controller can be combined in a circuit with an
NRGT 26-2 level transmitter.
To ensure proper use in all applications, please also read the Installation & Operating
Manuals for the system components used.
■ You can find the latest Installation & Operating Manuals on our website:
http://www.gestra.com
Improper use
There is a danger of death due to explosion if the equipment is used in potentially
explosive atmospheres.
Do not use the equipment in potentially explosive atmospheres.
Do not bring any equipment into service that does not have its own specific rating
plate.
The rating plate indicates the technical features of the equipment.
Applicable directives and standards
The equipment has been tested and approved for use in the scope governed by the following
directives and standards:
Standards:
■UL 60730-1 and CAN/CSA E60730-1
General Requirements for Automatic Electrical Controls
■UL 60730-2-15 and CAN/CSA E60730-2-15
Requirements for Automatic Electrical Water Level Sensing Controls

9NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
There is a risk of electric shock during work on electrical systems.
■ Always switch off the voltage to the plant before performing connection work.
■ Check that the plant is not carrying live voltage before commencing work.
Attempts to repair the equipment will cause the plant to become unsafe.
■ The NRR 2-50, NRR 2-51 level controller may only be repaired by the manufacturer,
GESTRA AG.
■ Only replace faulty equipment with identical equipment from GESTRA AG.
Basic safety information

10 NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Required personnel qualifications
Activity Personnel
Integration in control system Specialist staff Plant designer
Installation/
electrical connection/
bringing into service
Specialist staff
The equipment may only be installed, wired
and brought into service by qualified and
competent staff.
Operation Boiler service technician Staff trained by the plant operator.
Maintenance work Specialist staff
Fitting and maintenance work may only be
performed by authorized staff who have
undergone specific training.
Refits Specialist staff Persons trained by the plant operator to work
with pressure and temperature.
Notes on product liability
The manufacturer cannot accept any liability for damages resulting from improper use of the
equipment.

11NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Function
The NRR 2-50, NRR 2-51 level controller processes the level-dependent current signal from the
NRGT 26-2 level transmitter. In the controller, this input signal is standardized to 0 and 100% of
the boiler measuring range and shown as an actual value on the 7-segment LED display.
Level controller NRR 2-50: The level controller works with an electrically actuated control valve
as a 3-position stepping controller with proportional-plus-integral control action (PI controller).
If the actual value deviates from the set point, the electric actuator is triggered by two output
contacts and two flashing LEDs indicate whether the control valve is opening or closing.
The controller can be configured for fill or drain control.
A further output contact indicates when a MIN or MAX water level is reached (the desired function
is switch-selectable). After the off delay has elapsed, the output contact switches and the MIN or
MAX LED lights up.
Level controller NRR 2-51: The level controller works with an electro-pneumatically actuated
control valve as a continuous controller with proportional-plus-integral control action
(PI controller). In the event of deviations from the set point, it outputs a current of 4-20mA as
manipulated variable Y.
The controller can be configured for fill or drain control.
If the MIN or MAX water level is reached, after the off delay the MIN or MAX output contact
switches in the level controller, and the MIN or MAX LED lights up.
Level controller NRR 2-50, NRR 2-51: Faults in the level transmitter or the electrical connection
and setting errors are indicated as error codes on the 7-segment LED display. In the event of a
malfunction, the MIN and MAX alarm is triggered.
If faults occur only in the NRR 2-50, NRR 2-51 level controller, the MIN and MAX alarm is
triggered and the system is restarted.
Parameters can be changed or the MIN/MAX alarm simulated by turning the rotary knob.
To enable an external level display, the NRR 2-50 level controller is optionally available with a
4 - 20mA actual value output.

12 NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Supply voltage
24 VDC +/– 20%; PELV / CLASS2
Fuse
External M0.5A (medium time-lag)
Power consumption
4 W
Connection of level electrode/level transmitter (switch-selectable)
1 analog input 4-20mA, e.g., for the NRGT 26-2 level transmitter, 2-pole with shield.
Outputs:
NRR 2-50: 2 volt-free relay contacts, 8A 250V AC / 30V DC cos ϕ= 1 (control valve open/closed).
1 volt-free relay contact, 8A 250V AC / 30V DC cos ϕ= 1.
Off delay 3 seconds (MIN/MAX alarm, switch-selectable)
NRR 2-51: 2 volt-free relay contacts, 8A 250V AC / 30V DC cos ϕ= 1.
Off delay 3 seconds (MIN/MAX alarm)
1 analog output 4-20mA, max. output load 500ohms (manipulated variable Y).
Inductive loads must have interference suppression (RC combination) as specified by the
manufacturer.
NRR 2-50: 1 analog output 4-20mA, max. output load 500ohms, e.g., for an actual value display
(optional).
Indicators and controls
1 rotary knob with integrated push-button for testing the MIN/MAX alarm and setting the
parameters,
1 4-digit 7-segment LED display, green
2 red LEDs for MIN/MAX alarm,
2 yellow LEDs for control valve opening/closing (NRR 2-50 only)
1 4-pole code switch for configuration.
Terminal box
Terminal box material: base of black polycarbonate, front of gray polycarbonate
Wire size: 1 x AWG12 (4.0 mm2) solid, or
1 x AWG14 (2.5 mm2) stranded with sleeve acc. to DIN 46228, or
2 x AWG16 (1.5 mm2) stranded with sleeve acc. to DIN 46228
Terminal strips can be removed separately
Terminal box attachment: Mounting clip on support rail TH 35, EN 60715
Electrical safety
Pollution degree 2, overvoltage category II according to UL 60730-1
Protection
Terminal box: IP40 according to EN 60529
Terminal strip: IP20 according to EN 60529
As a UL open type, the equipment must be installed in a control cabinet.
Weight
Approx. 0.44lb (0.2kg)
Other information
Technical data

13NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Incorporated type 1 action operating control
Pollution degree 2, impulse voltage DC supply = 500V, AC output = 2500V
Ambient temperature
at power-on 32° ... 131°F (0° … 55°C)
in operation 14° … 131°F (-10° … 55°C)
Transport temperature
-4°F … 176°F (-20° … +80°C) (<100hours),
only switch on after a defrosting period of 24 hours.
Storage temperature
-4° … 158°F (-20° … +70°C), only switch on after a defrosting period of 24 hours.
Relative humidity
Max. 95%, non-condensing
Technical data

14 NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Niveauregler Level Controller Régulateur de niveau
MIN
MAX
19 20 16 17 18 21 22 23
Betriebsanleitung beachten See installation instructions Voir instructions de montage
NRR 2-50
250V ~ T2.5A
IP (IP20)40
GESTRA AG Münchener Str.77 28215 Bremen Made in Germany
Tamb = 55°C)T131°F (
OUT 4-20mA
500Ω
+
_
M0.5A
4W +
_
1
+12V
+
_
IN 4-20mA
NRG 2..-..
1 2 3 4 5 6 7 8
3
24V
±20%
Input rating: 24VDC, 4W Ambient temperature: 32-131°F (0-55°C) Wiring: Use Copper Conductors Only, Use 60/75°C Conductors, Use No.18 16 AWG Wire Size Only, Tightening: Torque 0.79Nm or 7lb in.
-
Use with accessory: NRGT 26-2
OPERATING CONTROL
E513189
Output rating : Pilot duty B300 / R300
NRR 2-50
Niveauregler Level Controller Régulateur de niveau
MIN
MAX
Betriebsanleitung beachten See installation instructions Voir instructions de montage
NRR 2-51
250V ~ T2.5A
IP (IP20)4040
GESTRA AG Münchener Str.77 28215 Bremen Made in Germany
Tamb = 55°C)T131°F (
3s
3s
OUT 4-20mA
500Ω
+
_
M0.5A
4W +
_
1
+12V
+
_
IN 4-20mA
NRG 2..-..
1 2 3 4 5 6 7 8
3
24V
±20%
Input rating: 24VDC, 4W Ambient temperature: 32-131°F (0-55°C) Wiring: Use Copper Conductors Only, Use 60/75°C Conductors, Use No.18 16 AWG Wire Size Only, Tightening: Torque 0.79Nm or 7lb in.
-
Use with accessory: NRGT 26-2
OPERATING CONTROL
E513189
Output rating : Pilot duty B300 / R300
NRR 2-51
Niveauregler Level Controller Régulateur de niveau
MIN
MAX
19 20 16 17 18 21 22 23
Betriebsanleitung beachten See installation instructions Voir instructions de montage
NRR 2-50
250V ~ T2.5A
IP (IP20)40
GESTRA AG
Münchener Str.77 28215 Bremen Made in Germany
Tamb = 55°C)T131°F (
OUT 4-20mA
500Ω
+
_
M0.5A
4W +
_
1
+12V
+
_
IN 4-20mA
NRG 2..-..
1 2 3 4 5 6 7 8
3
24V
±20%
Input rating: 24VDC, 4W Ambient temperature: 32-131°F (0-55°C) Wiring: Use Copper Conductors Only, Use 60/75°C Conductors, Use No.18 16 AWG Wire Size Only, Tightening: Torque 0.79Nm or 7lb in.
-
Use with accessory: NRGT 26-2
OPERATING CONTROL
E513189
Output rating : Pilot duty B300 / R300
NRR 2-50
Niveauregler Level Controller Régulateur de niveau
MIN
MAX
Betriebsanleitung beachten See installation instructions Voir instructions de montage
NRR 2-51
250V ~ T2.5A
IP (IP20)4040
GESTRA AG Münchener Str.77 28215 Bremen Made in Germany
Tamb = 55°C)T131°F (
3s
3s
OUT 4-20mA
500Ω
+
_
M0.5A
4W +
_
1
+12V
+
_
IN 4-20mA
NRG 2..-..
1 2 3 4 5 6 7 8
3
24V
±20%
Input rating: 24VDC, 4W Ambient temperature: 32-131°F (0-55°C) Wiring: Use Copper Conductors Only, Use 60/75°C Conductors, Use No.18 16 AWG Wire Size Only, Tightening: Torque 0.79Nm or 7lb in.
-
Use with accessory: NRGT 26-2
OPERATING CONTROL
E513189
Output rating : Pilot duty B300 / R300
NRR 2-51
Rating plate, bottom
Type
designation
Supply
voltage
Fuse, provided
by customer
Power
consumption
Disposal
information
Approvals
Fig. 2
Protection
Safety
information
Output contacts
Ambient
temperature
Connection
of level -
electrode/
level transmitter
Manipulated
variable Y
Rating plate of NRR 2-50, top Rating plate of NRR 2-51, top
Manufacturer
Serial number
Actual value
output
(optional)
Serial number
External
fuse for
output contacts
Rating plate, identification
Fig. 1
Niveauregler
Level Controller
Régulateur de niveau
MIN
MAX
Betriebsanleitung
beachten
See installation
instructions
Voir instructions de
montage
NRR 2-51
250V ~ T2.5A
IP (IP20)4040
GESTRA AG
Münchener Str.77
28215 Bremen
Made in Germany
Tamb = 55°C)T131°F (
3s
3s
OUT 4-20mA
500Ω
+
_
M0.5A
4W +
_
1
+12V
+
_
IN
4-20mA
NRG 2..-..
1
2
3
4
5
6
7
8
3
24V
±20%
Input rating: 24VDC, 4W
Ambient temperature: 32-131°F (0-55°C)
Wiring: Use Copper Conductors Only,
Use 60/75°C Conductors,
Use No.18 16 AWG Wire Size Only,
Tightening: Torque 0.79Nm or 7lb in.
-
Use with accessory: NRGT 26-2
OPERATING CONTROL
E513189
Output rating : Pilot duty B300 / R300
NRR 2-51
Niveauregler
Level Controller
Régulateur de niveau
MIN
MAX
19
20
16
17
18
21
22
23
Betriebsanleitung
beachten
See installation
instructions
Voir instructions de
montage
NRR 2-50
250V ~ T2.5A
IP (IP20)40
GESTRA AG
Münchener Str.77
28215 Bremen
Made in Germany
Tamb = 55°C)T131°F (
OUT 4-20mA
500Ω
+
_
M0.5A
4W +
_
1
+12V
+
_
IN
4-20mA
NRG 2..-..
1
2
3
4
5
6
7
8
3
24V
±20%
Input rating: 24VDC, 4W
Ambient temperature: 32-131°F (0-55°C)
Wiring: Use Copper Conductors Only,
Use 60/75°C Conductors,
Use No.18 16 AWG Wire Size Only,
Tightening: Torque 0.79Nm or 7lb in.
-
Use with accessory: NRGT 26-2
OPERATING CONTROL
E513189
Output rating : Pilot duty B300 / R300
NRR 2-50
NRR 2-50 NRR 2-51

15NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Factory default settings
Level controller NRR 2-50
■Off delay: 3 s
(default)
■Input set as voltage input,
please change using code switch S3.
■MAX switchpoint AL.Hi = 80%
■MIN switchpoint AL.Lo = 20%
■Set point SP = 50%
■Proportional band Pb = 20% of
set point
■Integral action time ti = 0%
■Dead band = +/– 5% of set point
■Valve travel time tt = 40 s
■Calibration value CAL.P = 100%
■Fill control function
■MIN/MAX output contact set as MAX alarm
Code switch c: S1, S2, S3, S4 OFF
Level controller NRR 2-51
■Off delay: 3 s
(default)
■Input set as voltage input, please change
using code switch S3.
■MAX switchpoint AL.Hi = 80%
■MIN switchpoint AL.Lo = 20%
■Set point SP = 50%
■Proportional band Pb = 20% of
set point
■Integral action time ti = 0%
■Dead band = +/– 5% of set point
■Calibration value CAL.P = 100%
■Fill control function
Code switch c: S1, S2, S3, S4 OFF

16 NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
The upper terminal strip of the equipment is live during operation.
There is a risk of serious injury due to electric shock.
Always cut off power to the equipment before working on the terminal strip (instal-
lation, removal connecting cables).
Danger
Switching the level transmitter input and changing the function
The input and function are determined by the setting of code switch c.
To make changes, you can access the code switch as follows:
sSwitch off the supply voltage.
■Detach the lower terminal strip. Fig. 3
■Insert a screwdriver between the terminal strip and the front frame, to the right and left of the
arrow markings.
■Release the terminal strip on the right and left by turning the screwdriver in the direction of the
arrow.
■Detach the terminal strip.
Changing the factory default settings
When your changes are complete:
■Insert the terminal strip.
■Switch the supply voltage back on. The equipment restarts
Fig. 3
c

17NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
If you wish to change the input or the function, set code switch cswitches S1 to S3 in
accordance with the table in Fig. 4.
Changing the factory default settings
Switching the level transmitter input and changing the function
Fig. 4
Code switch c
Level controller NRR 2-50 S 1 S 2 S 3
Output contact set for MAX alarm OFF
Output contact set for MIN alarm ON
Level Controller NRR 2-50, NRR 2-51
Input for connection of level
transmitter NRGT 26-2 * ON
Fill control OFF
Drain control ON
gray = factory setting
Attention
* When connecting the NRGT 26-2 level transmitter, please set the upper and lower
bounds of the measuring range only on the transmitter. To do this, please pay
attention to the NRGT 26-2 Installation & Operating Manual.
Do not move switch S4 on code switch c!
White toggle switch
c

18 NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Dimensions of the NRR 2-50, NRR 2-51
1Upper terminal strip
2Lower terminal strip
Key
3Terminal box
4Support rail TH 35, EN 60715
Fig. 5
43
1
2
1.81 in (46 mm)
2.91 in (74 mm)
4.72 in (120 mm)
0.6 in
(15 mm)

19NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Preparing for installation
If the control cabinet is to be installed outdoors, outside the protection of a build-
ing, environmental influences may adversely affect function.
■ Pay attention to the admissible ambient conditions in the technical data,
see page 12.
■ Do not operate the equipment if the temperature is below freezing.
◆ At temperatures below freezing, use a suitable heat source (e.g., control cabinet
heater, etc.).
■ Connect all parts of the plant to a central grounding point to prevent equalizing
currents.
■ Use UV-resistant cable ducts for routing the connecting cable.
■ Take further measures to protect the equipment from lightning, insects and
animals, and salty air.
You will need the following tools:
■Screwdriver size 1/8inch (3.2mm)

20 NRR 2-50, NRR 2-51 - USA - Installation & Operating Manual - 850699-00
Installation
Installing in the control cabinet
The NRR 2-50, NRR 2-51 level controller is clipped onto a type TH 35, EN 60715
support rail in the control cabinet. Fig. 5 4