Function .................................................................................................................................................5
System components ...............................................................................................................................5
Voltage table ......................................................................................................................................... 17
Declaration of conformity ......................................................................................................................19
3
4
Important Notes
Usage for the intended purpose
Use level electrodes NRG 16-11, NRG 17-11 and NRG 19-11 only in conjunction with level switch
NRS 1-7 for low-level limiting (low level alarm).
Safety note
The equipment must only be installed and commissioned by qualified and competent staff.
Retrofitting and maintenance work must only be performed by qualified staff – who through adequate
training – have achieved a recognised level of competence.
Danger
When loosening the electrode steam or hot water might escape.
This presents the danger of severe scalds to the whole body.
It is essential not to mount or dismantle the electrode unless the boiler pressure is
verified to be 0 bar. The electrode becomes hot during operation. Touching the hot
equipment presents the risk of severe burns to hands and arms. All installation and
maintenance work must only be performed when the equipment is cold.
Attention
The name plate specifies the technical features of the equipment. Note that any piece of
equipment without its specific name plate must neither be commissioned nor operated.
PED (Pressure Equipment Directive)
The equipment fulfills the requirements of the PED 97/23/EC. The equipment can be used with fluids of
group 1 and 2. With CE marking (except for equipment according to section 3.3 of the PED).
ATEX (Atmosphère Explosible)
The equipment constitutes a simple item of electrical equipment as defined in DIN EN 50020 section
5.4. According to the European Directive ATEX 94/9/EC the equipment may only be used in potentially
explosive atmospheres if it is provided with approved Zener barriers.
Applicable in Ex zones 1, 2 (1999/92/EC). The equipment does not bear an Ex marking. The suitability
of the Zener barriers is certified in a separate document.
Explanatory Notes
Scope of supply
NRG 16-11
1 Level electrode NRG 16-11, PN 40
1 Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
Explanatory Notes – continued –
Scope of supply – continued –
NRG 17-11
1 Level electrode NRG 17-11, PN 63
1 Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
NRG 19-11
1 Level electrode NRG 19-11, PN 160
1 Joint ring 27 x 32, form D, DIN 7603, 1.4301, bright-annealed
1 Disk with set screw (measuring surface extension) – optional
1 Retaining ring – optional
1 Installation manual
Description
The level electrode NRG 1...-11 detects the min. liquid level (low level alarm) in a steam boiler.
The operation of the electrode is based on the conductivity measuring principle using the electrical
conductivity of water for signaling one liquid level:
■ Low level alarm
The NRG 1...-11 is designed for use in conjunction with level switch NRS 1-7 as a self-monitoring low
level limiter with periodic self-checking (SMART) feature.
Application in steam and pressurised hot-water plants in accordance with TRD 604, sheet 1 and
sheet 2 (24 h/72 h operation) as well as EN 12952 and EN 12953.
The electrical equipment meets the requirements of the Regulations on Protection Circuits
DIN VDE 0116 (prEN 50156).
Function
The water level limiter comprises a level electrode type NRG 1...-11 and a level switch type NRS 1-7.
The level electrode NRG 1...-11 consists of two concentrically arranged electrodes (measuring electrode
and compensating electrode) which are isolated from each other by special insulating seals.
The level limiter operation is based on the conductive measuring principle using the electrical
conductivity of water for signaling water level. During normal, trouble-free operation the level electrode
tip is immersed in boiler water and no low level alarm is given. A low level alarm will only be raised if
the electrode tip is exposed for more than 3 seconds. A low level alarm will also be activated if the
insulating seals placed between the electrodes and the body are no longer pressure tight, allowing
water to penetrate into the body. However in this instance the alarm is caused by a malfunction of the
electrode, and confirmation should always be done by checking if there is water in the gauge glass.
The equipment combination NRG 1...-11 and NRG 1-7 provides fail safe protection against a first fault
in accordance with TRD 604.
System components
NRS 1-7
Level switch NRS 1-7. Two channel level limiter (redundancy) with periodic self-checking routine to
DIN VDE 0116.
5
6
Explanatory Notes – continued –
Design
NRS 1...-11
Screwed ¾" BSP, ISO 228-1,
Fig. 3, Fig. 4
Technical Data
NRG 16-11, NRG 17-11, NRG 19-11
Type approval
TÜV· WB·01-354
EG 01 202 931-B-01-0077
Service pressure
NRG 16-11: 32 bar at 238°C
NRG 17-11: 60 bar at 275°C
NRG 19-11: 100 bar at 311°C