Safe Coupling Relays
Both in mechanical engineering and in the process industry safe coupling relays are often used for coupling safety related signals, for example output signals of a safe control system to the periphery. The use of simple relays would result in the interruption of the safety chain and therefore a safe shutdown in case of failure could not be guaranteed.
This problem can be solved by using safe coupling relays. Redundantly designed, self-monitoring coupling relays allow the standardized coupling of safety related signals up to SIL 3 / PL e.
Typical fields of application for safe coupling relays include:
- Galvanically isolated coupling of digital 24 V and 230 V signals
- Safe coupling of sensor signals, e.g. pressure switch to controller (PLC)
- Contact multiplication with limited output power of the used safety PLC
- Filtering of test pulses sent by the safety controller
Safe coupling relays are often used as contact amplification for safe (small) control systems / safety PLCs. They fulfil the following standards: EN 60204-1; DIN EN ISO 13849-1; EN 62061; EN 50156-1; EN 746-2; IEC 61508 Parts 1-2 and 4-7; IEC 61511-1. EN 746-2, EN50156-1 or EN 81-20:2014; EN 81-50:2014 are also fulfilled by devices of this assembly.
| Type | Safety contacts / outputs (NO) |
Auxilliary contacts / outputs (NC) |
1 / 2 channel wiring | Width in mm | Reaction time | Approvals | |
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Safe coupling relay
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1 | 1 | 1 | 6.8 | < 20 ms* |  |
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3 | 1 | 1 | 22.5 | < 50 ms |  |
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3 |
1 |
1/2 |
22.5 |
< 20 ms* |
 |
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3 | 1 | 1/2 | 22.5 | < 7 ms* |
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3 | 1 | 1/2 | 22.5 | < 7 ms* |
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3 | 1 | 1/2 | 22.5 | < 20 ms* | |
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5 | 1 | 1 | 22.5 | < 50 ms |  |
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7 | 6 | 1 | 45 | < 20 ms* |
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7 | 6 | 1 | 45 | < 20 ms* |
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Coupling relay with forcibly guided contacts
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3 | 1 | 1 | 17.5 | < 40 ms |  |
Non safe coupling relays |
|
1 Wechsler |
1 | 6.2 | 15 ms | |
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2 Wechsler |
1 | 17.5 | < 40 ms | |
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2 Wechsler |
1 | 17.5 | < 40 ms | |
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4 |
1 | 31.5 | < 20 ms | |
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4 |
1 | 22.5 | |
*< 20 ms:
Applies for wiring via the safe inputs S14 & S12
Product Information:
Our safe coupling relays are not only suitable for furnaces in continuous operation, but also fulfil all current requirements of the relevant standards and are type-tested and certified by independent testing institutes such as TÜV-Rheinland.
The coupling relays, which are used for safe contact reinforcement, contact multiplication and safe signal isolation, are tested in accordance with ISO 13849-1. Our relays with their coupling function have also proven themselves in the process industry and shipping (Germanischer Lloyd).
The safe coupling relay SD1K impresses with its extremely slim design. With a width of only 6.8 mm, the SD1K meets all normative requirements for the safe coupling of safety-directed signals up to SIL3/PLe.
The ultra-slim SD1K requires only one-third of the space in the control cabinet compared to standard coupling relays with a 22.5 mm design – with the same level of safety. Whether in new installations or retrofits, this leads to space and thus cost savings.
In addition to its application in general mechanical engineering, the SD1K is also suitable for continuous use in firing systems and the process industry due to its special certification according to EN 50156-1, EN 746-2, and IEC 61511.
The safe coupling relay SK3D comes in a classic 22.5 mm wide housing, features 3 safe relay contacts, and is available in three voltage variants: DC 24 V, AC 115 V, and AC 230 V. It meets all normative requirements for applications up to SIL3 / PLe.
The SK3D is not only perfect for coupling functions and contact multiplication but can also safely couple 115/230 V high-voltage signals, e.g., from pressure monitors, to the control system thanks to its various voltage variants.
In addition to its application in general mechanical engineering, the SK3D is also suitable for continuous use in firing systems and the process industry due to its special certification according to EN 50156-1, EN 746-2, and IEC 61511.
Our safety relay SR3D comes in a classic 22.5 mm wide housing, features 3 safe relay contacts, and is available in three voltage variants: DC 24 V, AC 115 V, and AC 230 V. It meets all normative requirements for applications up to SIL3 / PLe.
It is designed as a fast coupling relay for the process industry and is used where fast response times are required, which cannot be achieved with a classic coupling relay.
In addition to its application in general mechanical engineering, the SR3D is also suitable for continuous use in firing systems and the process industry due to its special certification according to EN 50156-1, EN 746-2, and IEC 61511.
Our safety relay SR3D comes in a classic 22.5 mm wide housing, features 3 safe relay contacts, and is available in three voltage variants: DC 24 V, AC 115 V, and AC 230 V. It meets all normative requirements for applications up to SIL3 / PLe.
It is designed as a fast coupling relay for the process industry and is used where fast response times are required, which cannot be achieved with a classic coupling relay.
In addition to its application in general mechanical engineering, the SR3D is also suitable for continuous use in firing systems and the process industry due to its special certification according to EN 50156-1, EN 746-2, and IEC 61511.
Our safety relay SR3C comes in a classic 22.5 mm wide housing, features 3 safe relay contacts, and is available in three voltage variants: DC 24 V, AC 115 V, and AC 230 V. It meets all normative requirements for applications up to SIL3 / PLe.
It has been developed for general mechanical engineering and is at home in all applications where fast response times are required, which cannot be achieved with a classic coupling relay.
The safe coupling relay SK5C comes in a classic 22.5 mm wide housing, features five safe relay contacts, and meets all normative requirements for applications up to SIL3 / PLe.
The SK5C is perfect for coupling functions and contact multiplication where three relay contacts are not sufficient, but space is also limited.
In addition to its application in general mechanical engineering, the SK5C is also suitable for use in firing systems and the process industry due to its special certification according to EN 50156-1, EN 746-2, and IEC 61511.
Our safety relay SR7D comes in a 45 mm wide housing, features 7 safe relay contacts, and meets all normative requirements for applications up to SIL3 / PLe.
The SR7D is used when standard coupling relays reach their limits. With seven safe relay contacts, massive contact multiplication can be realized and reliably monitored through four signaling contacts and two semiconductor signaling outputs.
In addition to its application in general mechanical engineering, the SR7D is also suitable for continuous use in firing systems and the process industry due to its special certification according to EN 50156-1, EN 746-2, and IEC 61511.
The safe coupling relays SK3D and SD1K are especially designed for this application and enable the coupling of safety-related signals up to SIL 3 / PL e applications with a minimum width of 6.8 mm or 22.5 mm.
Aside from the use according to IEC61508 and IEC 61511, the recognised standards for furnaces were also taken into account. Both relays are type approved for the use in furnaces in continous operation according to EN 50156-1 and EN 746-2.
