Flowserve NRS 2-5 User Manual

NRS 2-5

Installation Instructions 810455-00

Level Switch Type NRS 2-5

1

Wiring Diagram

24V DC

11

Fig. 1

C28
A28

A30
C30

A24
C24

10

DC

12V DC

M

C16

C18

1

NRG 211

DC

NRS 2-5

Illustrated relay position:
Alarm, malfunction

A18

32

A22

C22

A20

C20

C 8
A 10
C 12

A 2
C 4
A 6

5

6

MIN

7

8

2

Fig. 2

12V DC 12V DC

NRS 2-5 NRS 2-5

MM

C16

C18

A18

10

1

NRG 211

32

C16

C18

A18

9

Dimensions

Fig. 3

A

B

NRS2-5

128.5

MIN

B

C

30.01

(6 TE)

3

Parts Drawings

1

2

MAX 70°C

NRS2-5

%

MAX 95%

IP 10

3

4

Fig. 4

MIN

4

Key

A

32 way screw-type connector

B

Fixing screw

C

19" Slide-in unit to DIN 41495

LED MALFUNCTION IN ELECTRODE

1

LED MALFUNCTION IN SUPPLY CABLE

2
3

LED LOW LEVEL ALARM

4

LED OPERATION

5

Switching contact ALARM (optocoupler)

6

Switching contact

7

Switching contact

8

Switching contact

9

Example of two low-level switches (redundancy)

10

Level electrode NRG 211

11

Test loop

MALFUNCTION (optocoupler)
ALARM (relay)
MALFUNCTION (relay)

5

Contents

Page

Important Notes

Safety note ...................................................................................................................... 7

Warning ........................................................................................................................... 7

Explanatory Notes

Scope of supply ..............................................................................................................7

System description ......................................................................................................... 8

Function .......................................................................................................................... 8

Design ............................................................................................................................. 8

Technical Data ................................................................................................................9

Installation

NRS 2-5 c/d ....................................................................................................................9

Wiring

NRS 2-5 c/d ..................................................................................................................10

Commissioning

Check wiring .................................................................................................................11

Apply mains voltage...................................................................................................... 11

Functional test .............................................................................................................. 11

Table 1........................................................................................................................... 11

Annex

Warning .........................................................................................................................12

Fault finding list .............................................................................................................12

Declaration of conformity ..............................................................................................13

6

Important Notes

Safety Note

Low level switches are essential safety devices that are required according to the
approvals for the equipment to which they are fitted.

Use low level switch NRS 2-5 only for indicating min. water level.
The equipment must only be installed by qualified staff.
Qualified staff are those persons who – through adequate training in electrical

engineering, the use and application of safety equipment in accordance with
regulations concerning electrical safety systems, and first aid & accident
prevention – have achieved a recognised level of competence appropriate
to the installation and commissioning of this critical safety device.

Warning

The terminal strip of the NRS 2-5 is live during operation. This presents
the danger of electric shock. Cut off power supply before mounting or
removing the case lid.

Explanatory Notes

Scope of supply
NRS 2-5c

1 Level switch, 19" slide-in unit, front panel to DIN 41494, part 5, 6 TE

(TE = division units; 1 TE = 5.08 mm)
2 Guide rails
1 Screw-type connector
1 Installation instructions

NRS 2-5d

1 Level switch, 19" slide-in unit, front panel to DIN 41494, par t 5, 6 TE
1 Installation instructions

7

Explanatory Notes – continued –

System description

The level switch NRS 2-5 is an analogue electronic amplifier for the capacitance
electrode NRG 211.

In combination with this level electrode it can detect low water level. In addition, the
level switch evaluates possible malfunction signals coming from the electrode and
monitors the electrode supply cable.

The level switch in combination with the level electrode can be used as par t of a
low-water level limiting system in steam boilers (separate approval).

Function

The NRS 2-5 has one channel and is provided with a power supply unit and a
voltage decoder. The supply voltage (12VDC) going to the electrode is converted
into a measuring voltage as a function of the operating mode. The signal decoder
assigns the measuring voltage to an operating mode which is indicated by LEDs at
the front panel of the NRS 2-5.

The level switch is designed for four operating modes:

■

Normal operation

■

Low-level alarm

■

Malfunction in level electrode

■

Malfunction in connecting cable

In the case of a low-level alarm or malfunctions the corresponding output relay will
be de-energized. Optocouplers are connected in parallel and assigned to the
output relays as additional switching elements.

Design
NRS 2-5c:

19" Slide-in unit with guide rails and 32 pole screw-type connector for installation in
19" magazines to DIN 41494 part 5. Front panel to DIN 41494, part 5, 6 TE

NRS 2-5d:

Spare 19" slide-in unit, front panel to DIN 41494, part 5, 6 TE

8

Technical Data
Input – measuring voltage

1–10 V DC (measuring voltage coming from level electrode)

Output – measuring voltage

12VDC (supply voltage going to level electrode)

Output

2 volt-free relay contacts
Max. contact rating with switching voltages of 24/115 /230V AC: 4 A resistive, 0.75A
inductive at cos ϕ 0.5.
Max. contact rating with switching voltage 24 V DC: 4A
Contact material: silver, hard-gold plated
2 optocouplers (npn), short-circuit protected due to inherent current limiting
characteristics, max. ratings: 70 V, 10 mA

Indicators and adjustors

1 green LED

ALARM, 2 LEDs MALFUNCTION, 1 LED OPERATION

Mains voltage

24 VDC

Power consumption

2VA

Case materials

NRS 2-5c
Front panel: aluminium, Fig. 7
NRS 2-5d
Front panel: aluminium, Fig. 7

Weight

NRS 2-5 c/d: approx. 0.6 kg

Installation

NRS 2-5c

1. Install plastic guide rails into 19" magazine.

2. Install screw-type connector.

3. Insert level switch into the 19" magazine and fasten with screws .

B

NRS 2-5d

1. Insert level switch into the 19" magazine and fasten with screws .

B

Tools

■

Screwdriver (5.5/100)

9

Wiring

NRS 2-5

Use screened four-core cable, conductor size 0.8 mm², max. cable length 500 m for
the supply of the electrode.

Wire screw-type connector according to wiring diagram, Fig. 1

Wiring diagram
See wiring diagram page 2.

Attention

■

To protect the relay contacts fuse the control circuit with T 2.5A or
according to TRD regulations (1.0 A for 72 h operation).

■

The screen must not make any other electrical contact.

Important Note

■

Connect screen only to terminal A18 of the level switch.

■

The monitoring of the level electrode and the monitoring of the
connecting cable can be integrated in the safety circuit. For this
purpose connect the safety circuit to the relay output

■

The rated voltage is indicated on the name plate.

■

When switching off inductive loads, voltage spikes are produced that
may impair the operation of control and measuring systems.
Inductive loads should be provided with commercial arc
suppressor RC combinations, e. g. 0.1 µF/100Ω.

MALFUNCTION.

Tools

■

Screwdriver for slotted screws, size 2.5, completely insulated acc. to VDE 0680

10

Commissioning

Check wiring

Check whether the NRS 2-5 and the associated system component NRG 211 are
wired according to the wiring diagram. Fig.1, Fig. 2

Apply mains voltage
Switch on mains supply. The green LED is illuminated. Fig. 4

4

Functional test
NRS 2-5 c/d

1. After switching on the mains voltage the green LED must be permanently

4

illuminated. Fig. 4

2. Lower the water level until it falls below the low-level mark.

The red LED at the level switch must light up.

3

3. Raise the water level until it exceeds the low-level mark. The red LED must

extinguish.

4. After removing the terminal box from the level electrode the yellow LED must

2

light up (malfunction in connecting wire).

5. Bridge terminals C16 and C18. The yellow LED must light up (malfunction in

1

electrode).

The measuring voltages of the different operating modes are represented in table 1.

Table 1

Measuring voltage U

≤1V

Decoded

M

Malfunction in electrode supply cable

(short circuit, interruption)
1V–4V Electrode exposed, low level
4V–7V Electrode submerged

≥ 9V

Malfunction in electrode (defective insulating seal,

leaking stuffing box)

11

Annex

Warning

The terminal strip of the NRS 2-5 is live during operation. This presents the
danger of electric shock.
Cut off power supply before inserting or removing the 19" slide-in unit and
before undertaking any installation or maintenance work.

Fault finding list

Fault: The level switch raises an alarm during normal operation.
Remedy: Check whether the green LED is illuminated. If not, check whether the

4

mains voltage is applied.

Fault: The yellow LED is illuminated.

1

Remedy: The level electrode is defective. Replace the equipment.
Fault: The yellow LED is illuminated.

2

Remedy: Check whether the connecting line to the electrode is interrupted.
If faults occur that are not listed above, please contact our subsidiary or agency in

your country.

12

Annex – continued –

Declaration of conformity

We hereby declare that the equipment NRS 2-5 c/d conforms to the following
European guidelines:

■

LV guideline 73/23/EWG version 93/68/EWG

■

EMC guideline 89/336/EWG version 93/68/EWG

which are based on the following harmonised standards:

■

LV standard EN 60947-5-1: 1991

■

EMC standard EN 50081-2, EN 50082-2

This declaration is no longer valid if modifications are made to the equipment without
consultation with us.

Bremen, 28th April 1997

GESTRA GmbH

Dr. Anno Krautwald

Dr. Christian Politt

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810455-00/999c · ©1999 GESTRA GmbH · Bremen · Printed in Germany

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