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Wieland offers two types of standstill monitors for machine safety applications.

  • Conventional standstill monitors in the SNS series that evaluate the motion via a pulse train signal.
  • Back-EMF (sensorless) monitoring using the SVM4001 series.

The SNS 4084K standstill monitor provides for the safe monitoring of the frequency of a signal at inputs I1 to I4 of the device. If the frequency of the impulses is higher than the frequency set at the rotary switches (0.1 – 99 Hz), outputs Q1/Q2 will switch off. This monitoring function can be used to detect the standstill or a lower, safer rotational speed of a machine.

In applications of this sort, a spring-actuated or magnet-actuated tumbler of an electric interlocking device, for example, can be controlled from the output of the device. The sensors for the detection of movement can, for example, be two inductive proximity switches or a rotary encoder connected to inputs I1 - I4. The frequency of the impulses to be monitored is set at the two rotary switches and splitter input T1, and is stored in the device on which the ENTER button is pressed while the voltage is applied to the device.

The SVM 4001K back-EMF sensorless standstill monitor detects movement simply by observing the voltage between windings of a motor. This product does not require external sensors and therefore lends itself well to retrofit application, and also offers an elegant and economical for any new machinery.

Read more:  White paper on standstill monitoring.

TechnologyBypassContactsSetpoint FrequencyTerminalsModelPart No.Datasheet
Pulse trainYes4 PNP0.5 - 99 Hz ScrewSNS 4074K-A R1.188.3640.0Download
Pulse trainYes4 PNP0.5 - 99 Hz Cage clampSNS 4074K-C R1.188.3650.0Download
Pulse trainYes4 PNP0.1 - 9.9 Hz ScrewSNS 4074K-A R1.188.3620.0Download
Pulse trainYes4 PNP0.1 - 9.9 Hz Cage clampSNS 4074K-C R1.188.3630.0Download
Pulse trainNo4 PNP0.5 - 99 Hz ScrewSNS 4084K-A R1.188.3480.0Download
Pulse trainNo4 PNP0.5 - 99 Hz Cage clampSNS 4084K-C R1.188.3490.0Download
Pulse trainNo4 PNP0.1 - 9.9 Hz ScrewSNS 4084K-A R1.188.3660.0Download
Pulse trainNo4 PNP0.1 - 9.9 Hz Cage clampSNS 4084K-C R1.188.3670.0Download
Sensorless (back-EMF)Yes2 NO24 V DCScrewSVM 4001K-AR1.188.4020.0Download
Sensorless (back-EMF)Yes2 NO24 V DCCage clampSVM 4001K-CR1.188.4030.0Download