Relay Modules

Weidmuller Relay modules and solid-state relays - Online Ordering

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SELECTION GUIDE RELAYS

Klippon® Relay
Reliable switching of power and signals Relay modules for various applications

Rely on the right one Electromechanical relay modules from Weidmüller
Introduction When selecting a relay module, there is a risk of incorrect dimensioning of the loads or signals to be switched. This can lead to malfunction or premature loss of the relay module. This brochure is intended to help you select the appropriate relay for each load or signal you wish to switch.

Solutions for more productivity Highly flexible design processes with Klippon® Relay
For more than 40 years, we have specialised in the optimisation of cabinet infrastructures. Our wide range of relay modules, solid-state relays and additional value-added services combine the highest standards with ultimate quality. Less wiring effort, housing optimisation through space saving, optimal marking and cost reductions our customers challenges are our motivation.
Our assortment impresses through reliability, longevity and safety. Supplemented by our digital data support, switching load consulting and online selection guides, we support our customers throughout the entire work process from the planning phase to installation and operation.

Selection guide for Switch to simple with Klippon® Relay

electromechanical

relay modules

Basics for the correct selection of relay modules

Switching of small resistive and inductive loads Selection table for signal relays

Switching of large resistive and inductive loads Selection table for power relays

Additional information on the selection tables Simple formulas for calculating individual values

Select contact materials suitable for your application Information of various contact material

Protect relay contacts effectively Selection criteria for protective circuits of inductive loads

Switching of capacitive loads Relays for LED lamps and devices with high inrush currents

Switching of very low power circuits Relay for forwarding control signals

Forced guided contacts explained in detail The difference to relays with conventional contacts

B10(d) + MTTF(d) Short explanation and example calculation

Online support and downloads

Fu Ti R
High sw Si
So Se S

TERMSERIES

lid-state rel

In our universal range, you will find an extensive portfolio of relay modules and solid-state relays in various designs.

Universal range

elay module

TERMSERIES

D-SERIES

s on
ays on uencies
s ns ety

pecial load

nsor isolati

gnal adapti

itching freq

Application range

ming functio

nctional saf

In our application range, you will find a tailor-made portfolio of products to increase your productivity and safety for various fields of application.

Power

Visit our website for more information www.weidmueller.com/klipponrelay
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Switch to simple with Klippon® Relay High-quality relays with unique all-round service
Whether switching, separating, amplifying, or multiplying: relays perform a multitude of different tasks in industrial applications. They have very specific characteristics and are available in almost innumerable varieties on the market. Klippon® Relay from Weidmüller makes your choice easy. Our worldwide unique all-round offer combines maximum relay variety with matching accessories and first-class service. We provide you with high-quality products that have been thought out down to the smallest detail, combined with comprehensive support from product selection to modern data services. Only with Klippon® Relay can you be sure to get the right relay for your specific needs and save time and money. That's our promise!
4

Visit our website for more information www.weidmueller.com/switchtosimple

uSniimqupely
5

Switch to simple with Klippon® Relay High-quality relays with unique all-round service
Switch to secure selection with Klippon® Relay The comprehensive relay portfolio with the perfect support
However complex your application environment, the wide Klippon® relay portfolio offers robust and efficient relays for every imaginable application. To ensure you find exactly what you need from our large selection, we offer comprehensive support in choosing the right product. We support you in selecting accessories and provide tips for installation and maintenance. This saves a lot of time and ensures you that you always get the optimum product for your specific application. Quick, easy and without selection errors!
Switch to reliable with Klippon® Relay Optimal relay selection for maximum plant availability
Is system availability your top priority? Then with our high quality Klippon® Relay portfolio you are on the safe side. We offer you comprehensive support to ensure you get the optimally dimensioned product for your application. With decades of experience in the relay segment, we choose the optimal products for you and ensure they are available within the shortest possible time. In this way you can reliably avoid unnecessary machine and system damage, minimise downtimes, and ensure system availability.
Switch to efficient with Klippon® Relay Innovative relay solutions for fast and easy wiring
Time is money. Especially in switch cabinet production and plant engineering. Relay modules and solid-state relays from the Klippon® relay portfolio can be installed particularly easily, quickly, and conveniently. The innovative PUSH IN technology shortens your wiring times and avoids incorrect wiring due to coloured pushers. Our KITs, consisting of relays with status LED and sockets with retaining clips, offer you even more convenience. They are supplied fully assembled and functionally tested for time-saving installation and fast commissioning with shorter processing times.
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Switch to maintainable with Klippon® Relay User-friendly relays for fast and error-free operation
Regardless of the application and environment, maintenance and repairs are unavoidable and must be carried out at regular intervals. With Klippon® Relay you can considerably reduce the required effort. We have focused on many details that make everyday maintenance work faster and easier. These include optimum marking options, clear status LED, consistent product labelling, connection markings, and much more. This makes work easier, faster, more cost-effective, and safer.
Switch to safe with Klippon® Relay Fully reliable special relays with comprehensive certification
Many machines and plants are applied worldwide and under the most diverse conditions. Therefore, they have to operate reliably under very different environmental conditions. In addition, they must comply with specific standards and directives. With Klippon® Relay, you have a range of products available to meet these requirements optimally. Whether high temperature ranges, strong vibrations, fast switching cycles, or specific safety requirements: With Klippon® Relay you will always find a suitable solution.
Switch to profitable with Klippon® Relay Multifunctional relay solutions for efficient warehousing
Warehousing and logistics play an important role in the assessment of total costs. With Klippon® Relay you can significantly reduce your logistic expenses. For example, we provide many of our products with Multivoltage inputs, which reduces the width of your stock. In addition, we can supply you with a wide range of convenient relay KITs that are pre-assembled, function and insulation tested. With these KITs you can reduce material numbers and speed up the storage and retrieval process considerably. An important contribution to process optimisation in everyday life.
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Find suitable relay modules for your application Basics for relay module selection

Electromechanical relays are a varied and cost-effective solution for a wide range of switching processes. They can be used for level and power adaptation and form interfaces between control, signalling and regulating equipment and peripherals. In spite of rising raw material prices, they are still very inexpensive and can be easily integrated into a wide variety of circuit types.
Relay modules from Weidmüller are extremely reliable, durable, and available in many different designs. The diversity of their applications in the various industrial sectors makes it necessary to select a suitable relay for each specific application. The following applies: Due to their design, relay modules are subject to mechanical and electrical wear, which must be taken into account when relay circuits are set up.

Switching of large AC loads
If large AC loads are switched, the relay can in principal be operated until the specified maximum value of switching voltage, current, or power is reached. However, when switching AC loads, the switching voltage has a much smaller influence on the service life of the relay contact than the switching current. The reason for this is that the arc that occurs when the relay is switched off usually extinguish automatically at the next zero crossing of the load current. In applications with inductive loads, an effective protective circuit should be provided, as otherwise a significantly reduced service life can be expected.

EN 60947-4-1 and EN 60947-5-1 describe various industrial reference loads such as resistive, capacitive, and inductive loads that stress the switching contact of a relay modules more or less. Electrical loads are formed out of a mixed load with ohmic, capacitive, and inductive load shares, though in practice, loads with a large inductive load share are used mostly. These include contactors, solenoid valves, motors, etc. We will take a closer look at these areas of application in the following.

Switching of large DC loads
Relays can only switch off relatively small direct currents because the zero crossing for extinguishing the arc is missing here. The maximum direct current value is also dependent on the switching voltage as well as on design conditions such as contact gap and contact opening speed. Corresponding current and voltage values are documented in load limit curves.
With undamped inductive DC loads, these values are lower because the energy stored in the inductance can ignite an arc that carries the current through the open contacts. The resulting arc significantly reduces the service life compared to an resistive load. An effective contact protection circuit can increase the service life of the contacts by 5 to 10 times compared to inductive loads that are not or unfavorably protected. Type 1N4007 freewheeling diodes are preferably suitable for this purpose.

Switching of utilization categories according to EN 60947
When selecting the relay, the maximum breaking capacity for AC loads and the DC breaking values taken from the load limit curves provide only rough reference values. In practice, however, this is not sufficient because real loads in industrial applications predominantly have inductive or capacitive load shares. Those variables can result in very different values for the service life.
To avoid these disadvantages, the contactor standard EN 60947 divides the loads into different use categories, such as DC-13 or AC-15. The standard is also partly applied to relays. However, users must be aware that these values are only partially suitable for practical use since all DC-13 and AC-15 test loads are highly inductive and operated without a protective circuit.
More precise statements on switching capacity and service life can be given based on specific application data. The more extensive the data collection, the more accurately the service life can be estimated for the respective applications and, if necessary, optimisation suggestions made. For critical applications, the users should determine the service life values themselves.

Switching of small resistive and inductive loads Selection table for signal relays

The table below helps you to select suitable relay modules for the specified loads. A service life of around 100,000 switching operations is assumed.

TERMSERIES + TERMSERIES-compact

D-SERIES
Universal range

Digital selection guide for electromechanical relay modules www.weidmueller.com/relayselector
Universal range

1 NO / 1 CO AgNi

RSS 1 CO AgNi

RSS 1 CO AgSnO

RCL 1 CO

RCL 1 NO AgSnO

RCL 1 NO AgSnO + W

RCL 2 CO

RCH 2 CO FG

DRI 1 CO

DRI 2 CO

DRM 2 CO

DRM 4 CO

Example Part No. Single relay 24 V DC input

Example Part No. KIT 24 V DC input

Insulation between input and output

Contact material

Width plugged on socket

Socket connection technologies

Max. Operating temperature

Resistive AC load

AC1 loads: Heaters 250 V AC

Inductive AC load

AC15 loads: Valves, contactors 250 V AC
AC3 loads: 1-phase motors 250 V AC

Resistive DC load

DC1 loads: Heaters 24 V DC

Inductive DC load

DC13 loads: Valves, contactors 24 V DC

Inrush current optimized

Recommended field of application

2773890000 reinforced insulation
AgNi 6.4 mm PUSH IN 60 °C < 5 A
< 1.5 A
< 0.5 A
< 3 A
< 1 A
-
Miniature switching relay for decoupling PLC's and for switching industrial small loads < 1.5 A in the smallest space.

4060120000 2618000000 reinforced insulation
AgNi 6.4 mm PUSH IN and screw 60 °C < 5 A
< 1.5 A
< 0.5 A
< 3 A
< 1 A
-
Miniature switching relay for decoupling PLC's and for switching industrial small loads < 1.5 A in the smallest space.

1984090000 2618020000 reinforced insulation
AgSnO 6.4 mm PUSH IN and screw 60 °C < 5 A
< 1.7 A
< 0.6 A
< 3 A
< 1.2 A
-

1984040000 2618100000 reinforced insulation
AgNi 12.8 mm PUSH IN and screw
60 °C < 12 A
< 3 A
< 1 A
< 8 A
< 2 A
-

Miniature switching relay for decoupling PLC's and for switching industrial small loads < 1.7 A in the smallest space.

Miniature industrial relay for decoupling PLC's and switching industrial small loads < 3 A.

1984080000 2618090000 reinforced insulation
AgSnO 12.8 mm PUSH IN and screw
60 °C < 13 A
< 3.5 A
< 1.5 A
< 9 A
< 3 A
80 A, 20 ms
Miniature industrial relay with a special contact for switching industrial small loads < 3.5 A with inrush currents up to 80 A / 20 ms. Additional information on page 18.

8866920000 2617930000 reinforced insulation AgSnO + W
12.8 mm PUSH IN and screw
60 °C
< 12 A
-
-
< 8 A
-
165 A, 20 ms 800 A, 200 µs
Miniature industrial relay with a special tungsten pre-contact for switching industrial loads with very high inrush currents up to 800 A / 200 s. Only very conditionally suitable for inductive loads. Additional information on page 19.

4058570000 2618400000 reinforced insulation
AgNi 12.8 mm PUSH IN and screw
60 °C < 6 A
< 1.5 A
< 0.7 A
< 4 A
< 1 A
-
Miniature industrial relay for decoupling PLC's, multiplying signals, and switching industrial small loads < 1.5 A.

2723360000 2706430000 reinforced insulation
AgNi 12.8 mm PUSH IN and screw
60 °C < 6 A
< 2.5 A
< 0.8 A
< 6 A
< 1.5 A
-
Miniature industrial relay with forcibly guided contacts according to EN 61810-3 type B for decoupling of PLC's and for switching of industrial small loads < 2.5 A.

7760056315 2576210000 basic insulation
AgSnO 16 mm PUSH IN and screw 55 °C < 10 A
< 3 A
< 1 A
< 8 A
< 2 A
-

7760056340 2576190000 basic insulation
AgSnO 16 mm PUSH IN and screw 55 °C < 5 A
< 1.5 A
< 0.5 A
< 4 A
< 1 A
-

Miniature industrial relay with optional mechanical test button for decoupling PLC's and switching industrial small loads < 3 A.

Miniature industrial relay with optional mechanical test button for decoupling PLC's, multiplying signals, and switching industrial small loads < 1.5 A.

7760056069 2576120000 basic insulation
AgNi 31 mm PUSH IN and screw 55 °C < 10 A
< 2.5 A
< 1 A
< 7 A
< 2 A
-
Miniature industrial relay with optional mechanical test button for decoupling PLC's, multiplying signals, and switching industrial small loads < 2.5 A.

7760056097 2576140000 basic insulation
AgNi 31 mm PUSH IN and screw 55 °C < 5 A
< 1.5 A
< 0.5 A
< 3.5 A
< 1 A
-
Miniature industrial relay with optional mechanical test button for decoupling PLC's, multiplying signals, and switching industrial small loads < 1.5 A.

The indicated currents only apply to the normally open contact. The data of the normally closed contact are to be set at approx. one third of the specified values. The real service life can be both above and below the specified value because each load stresses the switching contact differently and other environmental factors influence the service life of the switching contact, e.g. ambient temperature, mounting position, switching frequency, and many more. Therefore, these values are without guarantee and serve as orientation for better dimensioning. They may not be used as B10 or B10d values for the calculation of failure data such as MTTF or MTTFd either. The assessment of the maximum load capacity was carried out on the basis of many years of practical experience as well as life cycle tests under laboratory conditions.

Switching of large resistive and inductive loads Selection table for power relays

D-SERIES

The table below helps you

to select suitable relay

Universal

range

modules for the specified

loads. A service life of

around 100,000 switching

operations is assumed.

POWER

DRR 2 CO

DRR 3 CO

DRL 1 CO

DRL 2 CO

DRL 3 CO

DRL 4 CO

Example Part no. Single relay

Example Art. no. KIT 24 V DC input

Insulation between input and output

Contact material

Width plugged on socket

Socket connection technologies

Max. Operating temperature

Resistive AC load

AC1 loads: Heaters 250 V AC

Inductive AC load

AC15 loads: Valves, contactors 250 V
AC3 loads: 1-phase motors 250 V AC

Resistive DC load

DC1 loads: Heaters

Inductive DC load

DC13 loads: Valves, contactors 24 V DC

Inrush current optimized
Recommended field of application

2765020000 -
Basic insulation AgSnO 38 mm Screw 55 °C < 10 A
< 3.5 A
< 1.5 A
< 10 A

2765070000 -
Functional insulation AgSnO 38 mm Screw 55 °C < 10 A
< 3.5 A
< 1.5 A
< 10 A

2765110000 -
Basic insulation AgSnO 24 mm Screw 55 °C < 16 A
< 5.5 A
< 3.5 A
< 10 A

2765160000 -
Basic insulation AgSnO 24 mm Screw 55 °C < 10 A
< 4.5 A
< 2 A
< 7 A

2765220000 -
Basic insulation AgSnO 34 mm Screw 55 °C < 10 A
< 4,5 A
< 2 A
< 7 A

2765270000 -
Basic insulation AgSnO 44 mm Screw 55 °C < 10 A
< 4.5 A
< 2 A
< 7 A

< 2.5 A

< 4 A

< 3.5 A

-
Power relay (octal relay) for switching several industrial loads < 3.5 A.

-
Miniature power relay for switching industrial loads < 5.5 A.

-
Miniature power relay for switching several industrial loads < 4.5 A.

< 3,5 A
-
Miniature power relay for switching several industrial loads < 4.5 A.

< 3.5 A
-
Miniature power relay for switching several industrial loads < 4.5 A.

DRW 2 CO
2765600000 -
Basic insulation AgSnO 39 mm Screw 60 °C
< 16 A @ 250 V < 10 A @ 400 V
< 5.5 A
< 3.5 A
< 16 A

DRW 3 CO
2765650000 -
Basic insulation AgSnO 39 mm Screw 60 °C
< 16 A @ 250 V < 10 A @ 400 V
< 5 A < 3 A 1-phasig < 3 A 3-phasig
< 16 A

DRH 1 NO
N
S
1219850000 -
Basic insulation AgSnO 39 mm Screw 60 °C
< 16 A @ 400 V
< 7 A
< 4 A
< 16 A @ 24 V DC < 12 A @ 125 V DC < 10 A @ 220 V DC

< 4 A
Power relay with mechanical test button for switching multiple industrial loads < 5.5 A.

< 3.5 A
-
Power relay with mechanical test button for switching industrial loads < 5 A or a 3-phase electric motor < 3 A.

< 12 A @ 24 V DC < 5 A @ 125 V DC < 3 A @ 220 V DC
-
Power relay with blow out magnet and mechanical test button specially designed for switching industrial loads with high DC voltage up to 220 V DC 3 A.

DRH 2 NO
N
S
1220150000 -
Basic insulation AgSnO 39 mm Screw 60 °C
< 16 A
< 6 A
< 3,5 A
< 16 A @ 24 V DC < 7 A @ 125 V DC < 3 A @ 220 V DC

PWR 1 NO
1219480000 -
Basic insulation AgSnO 51 mm Screw 55 °C < 30 A
< 12 A
< 8 A
< 25 A

PWR 2 NO
1219550000 -
Basic insulation AgSnO 51 mm Screw 55 °C < 25 A
< 8.5 A
< 6 A
< 20 A

< 9 A @ 24 V DC < 2 A @ 125 V DC < 1 A @ 220 V DC
-
Power relay with blow out magnet and mechanical test button especially for switching industrial loads with high DC voltage up to 220 V DC 1 A.

< 7 A
-
Power relay (miniature contactor) with double contact opening for switching industrial loads < 12 A.

< 6 A
-
Power relay (miniature contactor) with double contact opening for switching industrial loads < 8.5 A.

Additional information on the selection tables Simple formulas for calculating individual values

Calculating the service life of the relay contacts for different switching currents
In the previous tables we gave you the maximum recommended currents at various loads for a service life of approx. 100,000 switching cycles. If you switch lower currents, the service life of the relay contacts will be extended. With the following formulas you can approximately calculate how the service life of the relay contacts will change.
Example: A 24 V DC solenoid valve with 200 mA current consumption should be switched with a 6.4 mm wide TERMSERIES RSS 1 CO relay. A solenoid valve corresponds to a DC13 load. According to the table, a switching current of max. 1 A is specified for the relay at this load. To calculate the expected service life, proceed as follows:

x =

ITable IApp

1 A

= 5

200 mA

Example: If the table shows a switching current of 2 A for a 250 V AC AC15 load, then these 2 A are also applicable for 120 V AC. At 24 V AC switching voltage, the expected service life increases four times to 400,000 switching cycles.
DC switching voltage: When switching DC loads, the switched voltage has a large influence on the maximum switching current of the relay contact. This can also be seen from the DC load breaking curve given in the data sheet. The following formulas can be used to roughly determine the maximal switching current for other DC switching voltages:
Example: A TERMSERIES RCL 1 CO relay with a DC13 load and a switching voltage of 110 V DC. According to the table a maximum of 2 A at 24 V DC applies to a DC13 load for a service life of 100,000 switching cycles.

Switching voltage [V DC]

nnew = 100,000 · x = 100,000 · 5 = 500,000

switching cycles

The expected service life when switching a 200 mA solenoid valve should be approx. 500,000 switching cycles.

DC load breaking capacity
Resistive load 300 200
100

IApp = Switching current in the application

IDC = DC Switching current at the DC switching voltage in the application

ILoad curve = DC Switching current from the load limit curve of the data sheet

INom = Continuous current from relay data sheet

ITable = Switching current from the selection table for the respective load

nnew = Service life at switching current in the application

= Reduction factor of the switching current

40 30

1 contact

10 0.1 0.2

0.5 1

2 5 10 20
Switching current [A]

The curve shows a maximum switching current of approx. 0.45 A with resistive load. This must now be set in relation to the rated current of the relay (16 A) from the data sheet and the value for a DC13 load from the table.

Calculating the switching currents for voltages that deviate from the values in the table
AC switching voltage: With AC loads, the switching current has the greatest influence on the service life. Therefore, the switching currents from the table can also be used for switching voltages up to 100 V AC. For values below 100 V AC, the service life increases at the same switching current:

ITable

2 A

x =

= 0.125

INom

16 A

IDC = ILoad curve · x = 0.45 A · 0.125 = 0.056 A = 56 mA

· at 24 V AC four times the service life · at 60 V AC twice the service life

To achieve 100,000 switching cycles, a DC13 load of 56 mA can be switched with a switching voltage of 110 V DC.

Select contact materials suitable for the application Information of various contact materials

Relay modules are used in a wide variety of industrial areas and environments. The relays must therefore be adapted to the various tasks by selecting suitable contact materials. The following applies: the load capacity of the contacts for voltage, current, and power depends essentially on the material used. To make the selection easier for you, we have compared the most important characteristics of the contact materials.

Criteria for the selection of the contact material:

· Welding tendency · Burn-off resistance · Contact resistance

· Material migration · Resistance to harmful gas atmospheres

Please obtain information when selecting a relay in this table:

Material Silver-nickel

Ag Ni

Characteristics
· Higher welding tendency than AgSnO · High burn-off resistance · Lower contact resistance than AgSnO · Mean material migration · Low resistance to harmful gas atmospheres

Recommended applications
· Suitable for low to high resistive and low inductive loads (solenoid valves, fans, heaters)
· Standard contact material for a variety of relays · Limited suitable for high inrush currents · Suitable for loads > 12 V/10 mA or 5 V/100 mA

Au Gold Ni Nickel Ag Silver W Tungsten Sn Tin 02 Oxygen

Ag Au Ni Silver-nickel flash gold plated

· Higher welding tendency than AgSnO · High burn-off resistance (gold just storage protection) · Lower contact resistance than AgSnO · Mean material migration · Low resistance to harmful gas atmospheres

· Suitable for low to high resistive and low inductive loads (solenoid valves, fans, heaters)
· The flash gold plating is a storage protection, but offers no functional improvement to AgNi · Limited suitable for high inrush currents · Suitable for loads > 12 V/10 mA or 5 V/100 mA

Ag Au

Silver-nickel hard gold plated

Silver-Tin-Oxide

Ag 02 Sn

· Very low resistance to burn-off · Lowest contact resistance · High resistance to harmful gas atmospheres
· Lower welding tendency than AgNi · High resistance to burn-off · Average contact resistance · Lower material migration than AgNi · Very low resistance to harmful gas atmospheresn

· Suitable for decoupling control inputs and other small resistive loads · Suitable for loads > 1 V/1 mA and < 30 V/10 mA · After switching loads > 30 V/100 mA, small powers can no longer be switched
reliably because the hard gold plating has been burned-off. Only the characteristics of the base contact material AgNi still apply.
· Suitable for medium to high resistive DC-loads and low up to medium inductive DC loads due to low material migration. Thanks to the low tendency to weld, it is also well suited for loads with higher inrush currents such as lamp loads, light capacitive loads, fluorescent tubes, etc.
· Suitable for loads > 12 V/100 mA

Tungsten

· Lowest welding tendency

· Very high resistance to burn-off · Highest contact resistance

· Low material migration

· Suitable for loads with very high inrush currents of up to 165 A/20 ms or 800 A/200 s (e.g. lamp loads, capacitive loads, fluorescent tubes, switched-mode power supplies etc.)
· Often used as a pre-making contact in parallel to AgSnO contacts

Protect relay contacts effectively Selection criteria for protective circuits of inductive loads

In our selection tables we specified the maximum recommended switching currents for inductive loads without protective circuits. If you want to increase the service life of the contacts, you must equip the relay contacts with an effective protective circuit.
The protective circuit on the coil side of a relay module can, for example, be implemented with an integrated or additionally pluggable freewheeling diode. However, this only protects the controlling periphery from the voltage peaks that occur in the coil of the relay module. The relay contact is usually not sufficiently protected against the voltage peaks of the inductive load to be switched, although with optimum dimensioning almost the same values for switching capacity or switching cycles can be achieved as with resistive load.

A protective circuits must be used to suppress the formation of electric arcs.
In the following, we will explain the correct installation of the protective circuit and the effectiveness of the most common types of protective circuit. There are various ways to install an effective protective circuits. For example, the protective circuit can be mounted either parallel to the relay contact or parallel to the load.
However, the protective measure should always apply directly to the source of the fault. Therefore, the protective circuit of the load is preferable to the circuit of the contact.

The largest reduction factor for the service life of a relay contact is the arc generated during switching off inductive loads. It is caused during the switching process by the energy stored in the coil and can destroy the contact through material evaporation and material migration.
With DC voltage and standing arc, the relay can even fail during the first switching cycle. Voltage peaks caused by electric arcs can reach values up to several 1,000 volts.

Advantages of a protective circuit at the load:
· When the contact is open, the load is still galvanically isolated from the operating voltage
· The switch-off peaks of the load cannot be coupled into the control lines running in parallel

Free-wheeling diodes

Varistors

RC modules

+ load

US UD

+ () ()
load

VDR

US U
VDR

+ () ()
load

US R
URC C

Free-wheeling diodes are used to protect against overvoltages caused by self-induction when an inductive DC voltage load is switched off (e.g. solenoid valves or electric motors). They ensure that the voltage peaks that occur are reduced to the value of the diode forward voltage (UD). However, this leads to a delay in the voltage drop and thus in the switch-off process of the load.

The functional principle of varistors is also based on breakdown voltages (UVDR). High energies can be dissipated, but this causes the component to aging. Therefore, the breakdown voltage is reduced over time and the leakage current is increased.

With RC modules, voltage peaks are compensated via a capacitor. Thanks to its special characteristics during charging and discharging the interference pulses are already filtered out during the voltage rise and not only when the breakdown voltage (URC) is reached.

Advantage: · Uncritical dimensioning · Very positive effect on the service
life of the contacts
Disadvantage: · Significantly extended switch off
process · Only suitable for DC voltage

Advantage: · Uncritical dimensioning · Suitable for DC and AC voltage · Slightly extended switch off
process
Disadvantage: · Complex and expensive with
increasing power · Low effect on the service life
of the contact

Advantage: · Suitable for DC and AC voltage · Slightly extended switch off
process
Disadvantage: · Exact dimensioning required · High inrush current · Low effect on the service life
of the contact

In order to implement a protective circuit tailored to the load, suitably dimensioned protective circuits are available as accessories from many manufacturers of inductive loads such as contactors or solenoid valves. This enables simple integration of the protective circuit on the load.

Switching of capacitive loads Relays for LED lamps and devices with high inrush currents

Loads with capacitive load shares, especially LED lamps, require extreme demands on switching contacts regardless of the voltage type. They cause highly energetic current peaks at the moment of switch-on. These can reach over 150 A and weld the contact.

Until a few years ago, the lighting of buildings and facilities was provided almost exclusively by light bulbs or fluorescent tubes of buildings and facilities. Nowadays, they are replaced by LED lamps, which consume much less power and are often much more durable. With retrofit solutions, such as LED lamps with E27 bases, this can be done quite easily. In new installations, LED lights are provided anyway.
However, problems often arise with relay circuits, such as those found in staircase illumination: LED lamps generate very strong inrush currents due to their design. Although these are much shorter than with conventional light sources, they can generate currents of over 150 A and thus weld the relay contact at the moment of switch-on.
Therefore, when switching LED lamps with standard relays, welded contacts occur after a very short time, sometimes even after the first switch-on. Furthermore, in more and more conventional industrial loads, such as solenoid valves and
Exemplary inrush current curve I
> 50 A

INOM

< 100 µs ...10 ms

contactors, capacitive load shares are hidden in input circuits, as these enable operation over a wide input voltage range. In order to switch such loads reliably, relays specially designed for this purpose are required. These relays have special contact materials and designs that can reliably switch significantly higher current peaks than conventional relays with e.g. AgNi as contact material. The characteristics of the various contact materials are listed below and assigned to recommended areas of application:

Special relay modules with tungsten contact for very high inrush currents of up to 800 A for 200 s
Single relay, 12.8 mm wide RCLS3T024W Complete module/KIT, 12.8 mm wide TRP 24VDC 1NO HCP TRS 24VDC 1NO HCP TRP 24-230VUC 1NO HCP ED2 TRS 24-230VUC 1NO HCP ED2
Special relay modules without tungsten contact for high inrush currents of up to 80 A for 20 ms
Single relay, 12.8 mm wide RCLS3L024W Complete module/KIT, 12.8 mm wide TRP 24VDC 1NO HC TRS 24VDC 1NO HC TRP 24-230VUC 1NO HC ED2 TRS 24-230VUC 1NO HC ED2

Order No. 8866920000
2617930000 1479810000 2663140000 2662980000
Order No. 1984080000
2618090000 1479780000 2663130000 2662970000

Solid state relays for short and high inrush currents (<10 ms) e.g. of LED lamps or devices with wide range inputs

Pluggable solid-state module DC output, 12 mm wide SSR 10-32VDC/0-35VDC 5A SSR 24VDC/0-24VDC 3,5A Pluggable solid-state module DC output, 5 mm wide SSS Relais 24V/24V 2Adc Complete module/KIT, 12.8 mm wide TOP 24VDC 24VDC5A TOS 24VDC 24VDC5A TOP 24VDC 24VDC3.5A TOS 24VDC 24VDC3,5A Complete module/KIT, 6.4 mm wide TOP 24VDC 24VDC2A TOS 24VDC 24VDC2A Pluggable solid-state module, AC output, 5 mm wide SSS Relais 24V/230V 1Aac Complete module/KIT, 6.4 mm wide TOP 24VDC 230VAC1A TOS 24VDC 230VAC1A

Order No. 1421450000 1132310000
4061190000
2618840000 1990960000 2618700000 1127630000
2618720000 1127170000
4061210000
2618420000 1127410000

HCP relay with tungsten contact in detail
Scan QR-Code and download the flyer

Solid state relays for short and high inrush currents (<10 ms) e.g. of LED lamps or devices with wide range inputs

Complete module, 6.1 mm wide MOS 24VDC/8-30VDC 2A MOS 24VDC/8-30VDC 2A E

Order No. 8937970000 1283230000

Visit our online catalogue for more information

Switching of very low power circuits Relay for forwarding control signals
Low power circuits with values below 30 V/10 mA are mainly used in applications where signals has to be transmitted to control inputs, e.g. to a PLC. Such low loads do not produce a sufficient arc at the contacts. However, this arc has two important functions: On the one hand, it ensures continuous cleaning of the contacts; on the other hand, it can penetrate non-conductive foreign layers at the contacts. Such foreign layers are usually created by oxidation or sulfidation of common contact materials such as silver (Ag), silver-nickel (AgNi), or silver-tin oxide (AgSnO). The foreign layers can increase the contact resistance after a short time to such an extent that reliable switching of low loads is no longer possible. For these reasons, gold (Au) is used as the contact material for relays switching small loads. It has proven itself due to its low and constant contact resistance and its resistance to ambient air containing sulphur.
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TERMSERIES The all-rounder. Modular relay modules from 6 mm width with extensive accessories, large selection of variants, and unlimited cross-connection possibilities.

Single relay, 5 mm wide RSS112024 Complete module/KIT, 6.4 mm wide TRP 24VDC 1CO AU TRS 24VDC 1CO AU

Order No. 4061590000
2618110000 1123000000

D-SERIES Industrial relay modules with innovative features and a large selection of variants for various applications.

Single relay, 21 mm wide DRM270024LT Au DRM570024LT Au

Order No. 7760056185 7760056189

Single relay, 12.8 mm wide RCL425024 Complete module/KIT, 12.8 mm wide TRP 24VDC 2CO AU TRS 24VDC 2CO AU

Order No. 4058580000
2618530000 1123730000

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21

Forced guided contacts explained in detail The difference to relays with conventional contacts

Relay modules with forcibly guided contacts use elementary relays according to IEC 61810-1 with a contact set according to IEC 61810-3. From the outside, they can hardly be differentiated from relays with conventional contacts, if at all. Due to their design, an opening failure of forcibly guided contacts can be reliably detected. Relays with such contacts have the following additional characteristics compared to relays with conventional contacts:
· Forcibly guided NC and NO contacts are designed in such a way that they cannot be closed at the same time
· If a contact of a forcibly guided contact set is welded, the antivalent contacts cannot close and the contact opening must be > 0.5 mm
· The contacts are located in contact chambers and are thus specially protected against other contacts and against the coil
Due to these normative requirements, the design and manufacturing effort for relays with positively driven contacts is much higher.

conventional relay

NNOO NNCC

NNOO

NNCC

oonnaall
NNoorrmmaall ooppeerraattiioonn aatt nnoonn eenneerrggiizzeedd ccooiill

wweellddeett ccoonnttaacctt
FFaauulltt ooppeerraattiioonn aatt nnoonn eenneerrggiizzeedd ccooiill

thh gguuiiddeedd

relay with forcibly guided contacts

NNOO NNCC

NNOO

NNCC >>00,,55mmmm

NNoorrmmaall ooppeerraattiioonn aatt nnoonn eenneerrggiizzeedd ccooiill

wweellddeett ccoonnttaacctt
FFaauulltt ooppeerraattiioonn aatt nnoonn eenneerrggiizzeedd ccooiill

The normally open contact (NO) is welded in this example. With standard relays, a normally closed contact (NC) can also be closed in case of the de-energized state. In this way, the NC and NO contacts can be closed at the same time and an opening failure cannot be reliably detected.
The normally open contact (NO) is welded in this example. In this case, relays with forcibly guided contacts cannot have a normally closed contact (NC) which is closed in the de-energized state. In this way, the NC and NO contacts cannot be closed at the same time and an opening failure can be reliably detected. It is mechanically ensured that the NC contact remains open with a minimum contact gap of 0.5 mm even in the de-energized state.

In addition, the standard distinguishes between two types of positive guidance, type A and type B:

Type
A

With type A relays, all contacts are mechanically positively driven with each other.
In an example of a six-pole relay with four NO contacts and two NC contacts, the four NO contacts are forcibly guided with both NC contacts. In this example, if one of the NO contacts welds, both NC contacts may no longer close if the relay is de-energized.
Type A relays with forcibly guided contacts can be found in our SAFESERIES Contact Extension.

Type
B

In a type B relay, not all contacts of a contact set are positively driven with each other.
In an example of a six-pole relay with four NO contacts and two NC contacts, the four NO contacts are forcibly guided with just one of the NC contacts. In this example, if one of the NO contacts welds, the non-force-guided NC contact can still close if the relay is de-energized. The other forcibly guided NC contact may not close. The status of the other NO contacts is undetermined. The non-force-guided NC contact can close because it is not forcibly guided to the other contacts in the relay. The contacts which are not forcibly guided must be specified in the data sheet.
Positively driven relays with changeover contacts (CO) are assigned to type B by the standard, only one NC or NO contact may be used per changeover contact. The reason for this is that the phenomenon of contact spring breakage cannot be excluded, so that in the event of a spring breakage of a changeover contact set, the NO and NC contacts of this contact set can be short-circuited.
Type B relays with forcibly guided contacts can be found in our TERMSERIES FG and RIDERSERIES FG.

SAFESERIES Contact Extension

Visit our online catalogue for more information

TERMSERIES FG

RIDERSERIES FG

B10(d) + MTTF(d) Short explanation and example calculation

1. Introduction of MTTF and MTBF Failure data such as MTTF (Mean Time To Failure) or MTBF (Mean Time Between Failure) are becoming increasingly important in the planning of machinery. This article will explain the importance of these values for electromechanical relays and solid state relays.
For the planning of electrical machines, it is necessary to know the MTBF values for the individual components such as relays in order to calculate the probability of failure for the entire system. MTBF is the mean time between failures, so it includes the mean operating and the mean repair time (MTTR = Mean Time To Repair). MTBF, MTTF and MTTR values are usually given in years. However, in the case of electronic components such as relays, the repair time is not determined because it is not economical to repair defective relays. They are replaced after they are worn. That is why relays are referred just to MTTF. So you can also say: MTBF is equal to MTTF for electromechanical relays and solid-state relays. The MTTF value is a statistical key figure/parameter. It is determined by tests and empirical values and therefore gives no guarantee of a certain service life.

MTTF

MTBF

MTTR

time
Operating time Repair time

Difference between MTTF and MTTFd The difference between MTTF and MTTFd (Mean Time to Failure dangerous) is that the MTTF value indicates the mean operating time to (any) failure, while the MTTFd value indicates the mean operating to a dangerous failure. Non-dangerous failures can lead to machine damage, but they are not relevant for safety considerations within the risk and hazard assessment. The MTTF value for individual components is usually obtained directly from the manufacturer. However, the manufacturer cannot provide an MTTFd value because he cannot ultimately assess which error in the application leads to a dangerous failure at the customer. In addition, the arrangement and alignment of several elements can also have an influence on the total time span until a dangerous failure. Above all, the possibility of executing a function in two channels and therefore redundant has a considerable influence on the MTTFd value of the entire system.
This means that the MTTFd must be determined by the person who develops the machine/ plant and also plans the safety functions. This is usually the developer or the designer. These persons can calculate the MTTFd.

MTTF for electromechanical relays B10-value
MTTF calculation using the B10-value B10d-value MTTFd calculation using the B10d-value

With electromechanical relays, the service life is strongly dependent on the number of switching cycles, the switched load and other environmental parameters such as temperature, mounting orientation, switching frequency and many more. This is because electromechanical relays are subject to mechanical and electrical wear, mainly due to contact erosion. For these reasons, the MTTF cannot be calculated from statistical values as it is the case with a solid-state relays, instead B10 values are determined. These B10 values are determined in complex and time-consuming test setups for various load cases, so there is only a selection of different B10 values and not every possible combination of switching current, load type and environmental parameters.
The B10 value indicates the nominal service life in switching cycles where 90% of a unit of tested relays still work. It is therefore the average number of switching cycles, according to which 10% of relays are to be expected to fail. This value is a statistical expected value that was determined on the basis of lifetime tests. In real applications, the lifetime values differ from the B10 value, as each load is different and the environmental parameters, such as humidity, air pollution, heat, vibrations, radiation, etc., have an influence on the service life.
The loads used for the determination of the B10 values are specified in the contactor standard EN 60947 in different categories of use suchas z.B. DC-13 or AC-15. However, users must be aware that these loads reflect practice only to a limited extent. Because all DC-13 and AC-15 test loads are highly inductive and operate without a protection circuit. Furthermore, the B10 values are determined at significantly higher switching frequencies than usual in reality. This is done to shorten the test execution time, otherwise tests would take years to deliver a result. An increased switching frequency also represents an increased load on the relay than usual in reality. However, it is almost impossible to compare B10 values of different providers. To compare different relays, the relays would have to be measured in exactly the same test setup. For this reason, the B10 values are often only provided by the manufacturer on request.
For the calculation of the MTTF value, the respective B10 value which most closely corresponds to the real application is converted into the following formula from the standard EN ISO 13849-1:
MTTF = B10 / (0,1 x annual switching cycles in the application)
The annual switching cycles in the application must be determined by the user himself.
The B10d indicates the number of switching cycles according to which a dangerous failures occur in 10 % of the units considered. The addition "d" stands for "dangerous". The value is for the creationa risk and hazard analysis relevant and thus also for the evaluation of the safety of a machine or plant. If there is no knowledge of the number of hazardous failures, EN ISO 13849-1 recommends the following calculation for the B10d value:
B10d = B10 x 2
This means that it is assumed that every second failure is a dangerous failure.
For the calculation of the MTTFd value, the respective B10d value which most closely corresponds to the real application is converted into the following formula from the standard EN ISO 13849-1:
MTTFd = B10d / (0,1 x annual switching cycles in the application)
The annual switching cycles in the application must be determined by the user himself.

2. Exemplary MTTF calculation of an electromechanical relay
B10 values available for the relay: 90,000 switching cycles at a DC13 load: 24 V DC / 1.5 A 250,000 switching cycles at an AC15 load: 230 V AC / 3 A 400,000 switching cycles at one AC1 load: 230 V AC / 6 A
Application: Switching a solenoid valve: 230 V AC / 2 A
Switching frequency of the relay: 3x per minute
Operating hours of the plant: 250 days a year 22 hours a day
1) First, the appropriate B10 value of the relay for the application is selected. Since a solenoid valve at 230 V AC is very similar to an AC15 load, this value is selected for the calculation:
250,000 switching cycles at an AC15 load: 230 V AC / 3 A
2) After that, the annual switching cycles of the relays must be determined. This is determined with the following formulas:
Formula signs: tZyklus = Mean time between two consecutive cycles in seconds hop = Average operating time in hours per day (0 - 24 hours) dop = Average operating time in days per year (0 - 365 days) nop = Average number of switching cycles per year tZyklus = 60 seconds / switching frequency of the relay per minute tZyklus = 60 seconds / 3 = 20 seconds nop = (dop x hop x 3600 s/h) / t nop = (250 days/year x 22 hours/day x 3600 seconds/hour) / 20 seconds nop = 990,000 switching cycles/year)
3) Calculation of the MTTF
MTTF = B10 / (0.1 x Annual switching cycles in the application) MTTF = 250,000 switching cycles / (0.1 x 990,000 switching cycles/year) MTTF = 2.52 years
The MTTF for the sample relay is therefore 2.52 years.
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3. MTTF for solid-state relays The MTTF value for solid-state relays is calculated from the failure rates of the individual electronic components, as they have no mechanical components that wear out due to mechanical abrasion or contact burn-off. The MTTF values of the Weidmüller solid-state relays can be found in the data sheet. The calculation was carried out in accordance with the standards SN 29500 and EN ISO 13849-1. The value refers to an ambient temperature of 40°C. When calculating the values for solid-state relays, the following things are not taken into account: · Electrical connections and plug-in connections · PCB (not included in the SN29500 standard) · Soldering process due to quality control processes in manufacturing
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Engineering Integrated engineering is the key to efficient product development. This requires a combination of engineering tools that can work together via interfaces and common data formats and sources. High-quality product information is required for planning in engineering systems such as Zuken or EPLAN. Weidmüller makes this information available in all common formats both in the data portals and on the Weidmüller website for you to download.
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Selection guide for electromechanical relay modules Our selection guide in digital and printed form support you in finding the right relay for safe and reliable switching of different loads: www.weidmueller.com/relayselector
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