GESTRA NRS 1-50 User manual
Original Installation &
Operating Manual
850694-00
Level Switch
NRS 1-50
For TWO electrodes
EN (USA)
English
2NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
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................................................................................................................. 13
Factory default settings ..................................................................................................................... 14
Dimensions of the NRS 1-50 .............................................................................................................. 15
Important notes .................................................................................................................................. 16
Safety information ......................................................................................................................... 16
Preparing for installation ................................................................................................................... 17
Installation.......................................................................................................................................... 18
Electrical connection.......................................................................................................................... 19
Supply voltage............................................................................................................................... 19
Connecting the level electrode....................................................................................................... 19
Connecting the safety circuit.......................................................................................................... 19
Connecting the signal output ......................................................................................................... 20
Wiring diagram of level switch NRS 1-50....................................................................................... 21
Wiring diagram for Class C protection against second faults with automatic prevention of
interlock deactivation in the event of malfunction........................................................................... 22
Example switching combinations ................................................................................................... 23
Key to example switching combinations......................................................................................... 24
3NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
Contents
Bringing into service .......................................................................................................................... 25
Changing the configuration............................................................................................................ 25
Checking the switchpoint and function........................................................................................... 26
Operation, alarm and test................................................................................................................... 27
Fault indications and troubleshooting............................................................................................... 27
Checking the level electrode.............................................................................................................. 29
Measuring level switch voltages .................................................................................................... 29
Emergency mode................................................................................................................................ 30
Emergency mode for water level limiters ....................................................................................... 30
Important notes .................................................................................................................................. 31
Action against high-frequency interference.................................................................................... 31
Interlock and interlock deactivation................................................................................................ 31
Checking switchpoints................................................................................................................... 31
Taking out of service.......................................................................................................................... 32
Disposal .............................................................................................................................................. 33
Returning decontaminated equipment.............................................................................................. 33
UL components................................................................................................................................... 33
4NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
Content of this Manual
Product:
■ Level Switch NRS 1-50, for TWO electrodes
First edition:
BAN 850694-00/09-2021cm
© 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
NRS 1-50
1 level switch NRS 1-50
1 Installation & Operating Manual
5NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
How to use this Manual
This Installation & Operating Manual describes the correct use of the NRS 1-50 level switch. It
applies to persons who integrate this equipment in control systems, install, bring into service, op-
erate, maintain and dispose of this equipment. Anyone carrying out the above-mentioned 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
6NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
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.
7NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
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 145psi (10bar) and 356°F (180°C) may be designed to withstand a
pressure of 870psi (60bar) and a temperature of 527°F (275°C), for example, which is therefore
not necessarily its operating point.
8NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
Usage for the intended purpose
The NRS 1-50 level switch is used in conjunction with NRG 1...-50 level electrodes as a
water level limiter for steam boilers and hot water installations.
Water level limiters switch off the heating when the water drops below the set low water level
(LW). The NRS 1-50 is classified as a protective control Class B (C) in accordance with UL 60730-
1.
When used as intended, the NRS 1-50 level switch is combined in a circuit with the level elec-
trodes stipulated by the directives or standards below:
Level electrodes NRG 1...-..
UL 60730-2-15,
CAN/CSA E60730-2-15
NRG 16-50 NRG 17-50 NRG 19-50
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
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
9NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
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 NRS 1-50 level switch may only be repaired by the manufacturer, GESTRA AG.
■ Only replace faulty equipment with identical equipment from GESTRA AG.
Basic safety information
10 NRS 1-50 For TWO electrodes - USA - Installation & Operating Manual - 850694-00
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.
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