Flowserve NRS 1-50 User Manual

GESTRA

GESTRA Steam Systems

NRS 1-50

For ONE Electrode

Installation Instructions 818987-00

Level Switch NRS 1-50

English

Contents

Page

Application

Usage for the intended purpose ..............................................................................................................4

Function .................................................................................................................................................4

Directives and Standards

Pressure Equipment Directive (PED) 97/23/EC ........................................................................................

Functional Safety acc. to IEC 61508 ........................................................................................................

VdTÜV Bulletin “Wasserstand 100” (= Water Level 100) ..........................................................................

Approvals for Marine Applications ........................................................................................................... 5

LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility) .......................................................5

ATEX (Atmosphère Explosible) .................................................................................................................5

Functional Safety acc. to IEC 61508

Safety characteristics of the subsystem NRG 1...-50 / NRS 1-50 .............................................................

Terms and abbreviations .........................................................................................................................6

Determination of the Safety Integrity Level (SIL) for safety-related systems .............................................7

Technical Data

NRS 1-50

Name plate / marking ...........................................................................................................................10

Dimensions and Functional Elements

NRS 1-50..............................................................................................................................................11

Important Notes

Safety note ...........................................................................................................................................12

Scope of supply ....................................................................................................................................12

Installation

..........................................................................................................................................8 – 9

5 5 5

Mounting level switch NRS 1-50 ........................................................................................................... 13

Contents - continued -

Page

Electrical Connection

Mains supply ........................................................................................................................................13

Connection of level electrode ................................................................................................................ 13

Connection of safety circuit ...................................................................................................................13

Connection of logic unit (standby input).................................................................................................13

Connection for signal output .................................................................................................................13

Tools .....................................................................................................................................................14

Wiring diagram for level switch NRS 1-50 .............................................................................................15

Schematic representations of arrangements .........................................................................................16

Explanatory notes to schematic respresentations .................................................................................. 17

Basic Settings

Factory setting ......................................................................................................................................18

Commissioning Procedure

Checking switchpoint and function .......................................................................................................19

Operation, Alarm and Test

Indicators and adjustors ........................................................................................................................20

Troubleshooting

Indication, diagnosis and remedy ..................................................................................................20 – 21

Checking level electrode

Measuring voltage across level electrode ..............................................................................................22

Further Notes

Action against high frequency interference ...........................................................................................23

Interlock and interlock deactivation .......................................................................................................23

Checking the switchpoints .................................................................................................................... 23

Decommissioning / replacing level switch .............................................................................................23

Disposal................................................................................................................................................23

Note on the Declaration of Conformity / Declaration by the Manufacturer .......................................23

Application

Usage for the intended purpose

The level switch NRS 1-50 is used in conjunction with level electrode NRG 1...-.. to limit the water level in steam boilers and (pressurised) hot-water plants. Water level limiters switch off the heating when the water level falls below the set minimum level (low water).

Depending on the speciﬁed directives or standards, the level switch NRS 1-50 is intended to be used in combination with the following level electrodes:

Level electrode NRG 1...-..

PED Pressure Equipment Directive 97/23/EC + Functional Safety IEC 61508 SIL 3

VdTÜV Bulletin “Wasserstand 100” (= Water Level 100)

Marine applications GL/LR Directives

Function

The level switch NRS 1-50 is designed for different electrical conductivities of the boiler water and for connecting one level electrode.

When the water level falls below the low level the level electrode is exposed and a low level alarm is triggered in the level switch. This switchpoint is determined by the length of the electrode rod (level electrode NRG 1...-50, NRG 1...-11, NRG 16-36).

After the de-energizing delay has elapsed, the two output contacts of the level switch will open the safety circuit for the heating. The switching-off of the heating is interlocked in the external safety circuit and can only be deactivated when the level electrode enters the water again.

In addition two signalling contacts for external signalling devices close instantaneously. An alarm will also be raised if a malfunction occurs in the level electrode and/or the electrical connec-

tion. If the level electrode is installed in an isolatable level pot outside the boiler, make sure that the con-

necting lines are rinsed regularly. During the rinsing process the water level cannot be measured in the level pot for 5 minutes. The level switch therefore bypasses the level electrode and monitors the rinsing and bypass time (standby input, controlled by the logic unit SRL 6-50).

If the connecting lines for steam ≥ 40 mm and water ≥ 100 mm, the installation is considered to be internal. In this case the rinsing processes do not have to be monitored.

An automatic self-testing routine monitors the safety functions in the level switch and the level electrode. In the event of a malfunction the safety circuit opens instantaneously and switches the heating off.

Alarm and error messages are indicated by LEDs and an alarm can be simulated by pressing the test button.

NRG 16-50 NRG 17-50 NRG 19-50 NRG 111-50 NRG 16-36

NRG 16-50 NRG 16-11

NRG 16-50S NRG 16-11S NRG 16-38S NRG 16-39S

NRG 17-50 NRG 17-11

NRG 19-50 NRG 19-11

NRG 111-50 NRG 111-11

NRG 16-36

Directives and Standards

Pressure Equipment Directive (PED) 97/23/EC

Water level limiters are safety accessories as deﬁned in the Pressure Equipment Directive (PED). The level switch NRS 1-50 in conjunction with level electrode NRG 1...-50 and NRG 16-36 is EC type approved according to EN 12952/EN 12953. These Directives state, among other things, the require ments made on limiting systems and equipment for steam boiler plants and (pressurised) hot-water installations.

Functional Safety acc. to IEC 61508

The level switch NRS 1-50 is certiﬁed acc. to IEC 61508 only if used in combination with level elec trode NRG 1...-50 / NRG 16-36 . This standard describes the functional safety of safety-related electri cal/electronic/programmable electronic systems.

The equipment combination NRG 1...-50 or NRG 16-36 + NRS 1-50 corresponds to a type B subsys tem with Safety Integrity Level (SIL) 3.

VdTÜV Bulletin “Wasserstand 100” (= Water Level 100)

The level switch NRS 1-50 in conjunction with the level electrodes NRG 1...-50, NRG 1...-11 and NRG 16-36 is type approved according to the VdTÜV Bulletin “Water Level 100”. The VdTÜV Bulletin “Wasserstand (= Water Level) 100” speciﬁes the requirements made on water level control and limiting equipment for boilers.

Approvals for Marine Applications

The level switch NRS 1-50 in conjunction with level electrodes NRG 16-50S/NRG 16-11S/NRG 16-38S and NRG 16-39S is approved for marine applications. We can present approvals issued by Germanischer LLoyd and Lloyd’s Register.

LV (Low Voltage) Directive and EMC (Electromagnetic Compatibility)

The level switch NRS 1-50 meets the requirements of the Low Voltage Directive 2006/95/EC and the EMC Directive 2004/108/EC.

ATEX (Atmosphère Explosible)

According to the European Directive 94/9/EC the level switch NRS 1-50 must explosive areas.

not be used in potentially

Note

The level electrodes NRG 1...-50, NRG 1...-11 and NRG 16-36 are simple items of elec trical equipment as speciﬁed in EN 60079-11 section 5.7. According to the European Directive 94/9/EC the equipment must be equipped with approved Zener barriers if used in potentially explosive areas. 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. Note that the requirements of the IEC 61508 are not met if the NRG 1...-50, NRG 1...-11 and NRG 16-36 + Zener barriers + NRS 1-50 are interconnected!

Functional Safety acc. to IEC 61508

Safety characteristics of the subsystem NRG 1...-50 / NRS 1-50

The level switch NRS 1-50 is certiﬁed acc. to IEC 61508 if used in combination with level electrode NRG

1...-50 / NRG 16-36. The combination NRG 1...-50 / NRG 16-36 / NRS 1-50 corresponds to a type B subsystem with Safety

Integrity Level (SIL) 3. Type B means that the behaviour under fault conditions of the used components cannot be completely determined. The functional safety of the equipment combination refers to the detection and evaluation of the water level and, as a consequence, the contact position of the output relays.

The design of the equipment combination NRG 1...-50 / NRG 16-36 / NRS 1-50 corresponds to the ar chitecture 1oo2 D. This architecture consists of two channels that detect and diagnose faults in each other. If a fault is detected, the equipment combination NRG 1...-50 / NRG 16-36 / NRS 1-50 will go to the safe state, which means that the contacts of both output relays will open the safety circuit.

Safety characteristics

General 3 1oo2 D 20 20

Level switch NRS 1-50 alone 98.54 % 1.18 x 10

Level switch NRS 1-50 in conjunction with

one level electrode NRG 1...-50, NRG 16-36

Fig. 1

Terms and abbreviations

Terms

Abbreviations

Safety Integrity Level

SIL

Lifetime (a) Functional safety: Lifetime in years

Safe Failure Fraction

SFF

Probability Failure per Demand

(Low Demand) PFD

Probability Failure per Hour

PFH

Classification of the Safety Integrity Level acc. to IEC 61508

Percentage of failures without the potential to put the safety-related system into a dangerous state

Average probability of failure on demand for low demand mode (once a year)

Probability of failure per hour

Failure rate for all dangerous undetected failures (per hour) of a channel of a subsystem

Fig. 2

SIL Architecture

SFF PFD

98.17 % 1.69 x 10

-4

Description

Lifetime

(a)

PFH

3.73 x 10

4.54 x 10

Proof Test

Interval (a)

-8

7.33 x 10

9.33 x 10

-8

Functional safety acc. to IEC 61508 - continued -

Determination of the Safety Integrity Level (SIL) for safety-related systems

Level electrode, level switch and actuators (auxiliary contactor in safety circuit) are subsystems and together constitute a safety-related system that executes a safety function.

The speciﬁcation of the safety-related characteristics Fig. 1 refers to the level electrode and the level switch including the output contacts. The actuator (e. g. an auxiliary contactor in the safety circuit) is installation speciﬁc and, according to IEC 61508, must be considered separately for the whole safetyrelated system.

Table Fig. 3 shows the dependence of the Safety Integrity Level (SIL) on the average probability of failure on demand of a safety function for the whole safety-related system (PFD is here considered for a water level limiter, which means that the frequency of demands for operation of the safety-related system is no greater than one per year.

). The “Low demand mode”

sys

Low demand mode PFD

-5

... < 10

-4

... < 10

-3

... < 10

-2

... < 10

-4

-3

-2

-1

≥ 10 ≥ 10 ≥ 10 ≥ 10

sys

Safety Integrity Level

(SIL)

4 3 2 1

Fig. 3

The table in Fig. 4 indicates the attainable Safety Integrity Level (SIL) as a function of the Safe Failure Fraction (SFF) and the Hardware Fault Tolerance (HFT) for safety-related systems.

Hardware Fault Tolerance (HFT) for type B

0 1 2

SIL 1 SIL 2 SIL 1 SIL 2 SIL 2

SIL 3 SIL 4 90 % – < 99 %

SIL 3 60 % – < 90 %

SIL 3 SIL 4 SIL 4 ≥ 99 %

Safe Failure Fraction

(SFF)

< 60 %

Fig. 4

Technical Data

NRS 1-50

Supply: Mains voltage

24 VDC +/– 20%, 0.3 A or 100 – 240 VAC +10/–15 %, 47 – 63 Hz, 0.2 A External fuse

0.5 A (semi-delay)

Power consumption

7 VA Response sensitivity (Electrical conductivity of water at 25 °C)

> 0,5 ... < 1000 µS/cm or > 10 ... < 10000 µS/cm

Inputs: Connection of level electrode

1 input for level electrode NRG 1...-50, NRG 1...-11, NRG 16-36, 4 poles, with screen.

Stand-by input

1 volt-free input, 24 V DC, for monitoring the purging and bypass time. Max. bypass time: 5 minutes.

Outputs: Safety circuit

2 volt-free make contacts, 24 V DC - 250 V AC, max. 6 A (resistive/inductive), Contact material AgNi. Delay of response: 3 seconds, 15 sec. for marine applications. Provide inductive loads with RC combinations according to manufacturer's speciﬁcation to ensure interference suppression.

Signal output

2 volt-free outputs for instantaneous external signalling, 24 - 230 V AC/DC, max. 100 mA.

Indicators and adjustors

2 buttons for test and diagnosis, 2 red/green LEDs for indicating the operating mode and alarm. 3 red LEDs for diagnosis.

Housing Housing material: base: polycarbonate, black; front: polycarbonate, grey. Conductor size: 1 x 4.0 mm 1 x 2.5 mm 2 x 1.4 mm

per stranded wire with sleeve to DIN 46228 or

per stranded wire with sleeve to DIN 46228;

solid per wire or

terminal strips can be detached Fixing of housing: Mounting clip on supporting rail TH 35, EN 60715

Electrical safety

Degree of contamination: 2, overvoltage category III to EN 61010-01. Protection

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

Weight

approx. 0.5 kg

+ 16 hidden pages