Motion Relais

Our motion relays are suitable for the safe monitoring of 1- to 3-phase motors with or without encoders in machines or systems.


Motion relays comprise two types of motion monitoring devices, namely standstill monitors and speed monitors. Neither incremental encoders nor proximity sensors are required to measure the operating status with standstill monitors. Safe monitoring of the machine or system with speed monitors is carried out together with incremental encoders or proximity sensors.



SVM 4001K-A

The device has screw terminals

SVM 4001K-C

The device has push-in terminals

  • Standstill monitoring
  • Monitoring of electrical locking devices
  • Activation of spring-loaded guard locking devices
  • Monitoring of low speeds in set-up mode

The SVM 4001K device monitors machines whose three-phase AC drive units do not have sensors for detecting movement; the relays of the standstill monitor switch to the idle position when the drives start to move or when faults are detected.

  • Sensorless monitoring of 1-phase and 3-phase motors
  • Safe, adjustable voltage monitoring
  • Automatic operation
  • bis PL e /Kategorie 4 (EN ISO 13849-1)
  • bis SILCL 3 (EN 62061)



SNS 4074K 

The device has a bypass input with which the safety-related bypassing of the monitoring function is possible, e.g. when a safe position is reached. In this case, the signal must correspond to at least the safety category of the selected monitoring function.

SNS 4084K 

The device has an input for start-up bridging with which the safe outputs can be switched off while a machine is at a standstill. This can be used, for example, to activate a spring-loaded guard locking of a safety device when the machine starts up.

  • Standstill monitoring
  • Monitoring of electrical locking devices
  • Activation of spring-loaded guard locking devices
  • Monitoring of low speeds in set-up mode

The SNS 4084K standstill monitor ensures safe monitoring of the frequency of a signal at inputs I1 to I4 of the device. If the frequency of the pulses is higher than the frequency set on the rotary switches (0.1 - 99 Hz), the outputs Q1/ Q2 switch off. This monitoring function can be used to detect the standstill or low, safe speed of a machine. 

In such applications, for example, a spring- or solenoid-operated guard locking of an electrical locking device can be controlled by the outputs of the device. The sensors for detecting the movement can be, for example, two inductive proximity switches or an incremental encoder, which are connected to inputs I1 - I4. The frequency of the pulses to be monitored is set on the two rotary switches and is stored in the device by pressing the ENTER button while the voltage is being applied to the device.

  • Reliable monitoring of dynamic input signals
  • Adjustable monitoring frequency 0.1 - 99 Hz
  • 4 selectable operating mode groups
  • Single or dual-channel control
  • Manual or automatic start
  • Cross-circuit detection
  • 4 wear-free safe semiconductor outputs
  • up to PL e /category 4 (EN ISO 13849-1)
  • up to SILCL 3 (EN 62061)


Safety has been our daily business – for more than 30 years. On the way to CE marking and safe operation, we are your reliable partner and contribute our experience to your project. Whether training or consulting: We put together your individual all-round carefree package for  thestandard-compliant implementation of your machines. We support manufacturers and operators either in specific sub-steps such as inspection and overrun measurement, risk assessment of machines or validation of safety functions according to EN ISO 13849-2, or we accompany them holistically through the CE process up to CE conformity assessment according to machine directives.

Carefree to ce marking of your Machines


Safety - Catalog

0860.1 | 29 MB

Safety Service - Machine Safety

0875.1 | 477 KB


What is a standstill monitor?

A standstill monitor monitors the frequency of signals at the inputs and recognises when a machine comes to a standstill or reaches a low, safe speed.

What safety levels do the standstill monitors from Wieland Electric fulfil?

The standstill monitors fulfil up to PL e / category 4 (EN ISO 13849-1) and up to SILCL 3 (EN 62061).

What is the main difference between the SNS 4074K and SNS 4084K models?
  • SNS 4074K Has a bypass input for safety-related bypassing of the monitoring function.
  • SNS 4084K Has an input for start-up bypass, which makes it possible to switch off the safe outputs during standstill.
How does the SVM 4001K sensorless standstill monitor work?

The SVM 4001K monitors machines whose three-phase AC drive units have no sensors to detect movement. When the drives start to move or when faults are detected, the relays of the standstill monitor switch to the idle position.

Which standards do the standstill monitors fulfil?
  • EN ISO 13849-1
  • EN 62061
What certifications do the standstill monitors have?
  • TÜV
  • cULus Listed

Do you need further product information?
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