Safety encoder: EK8S, AK8W, AK8Y, EK8W, AK8H

Designation

Requirement

Safety requirements

≥ SIL 2

Diagnostic coverage (DC)

≥ 90%

Fault presumptions

According to EN 61800‑5‑2:2017, table D.8

Monitoring of the phasor length "r"

with

a = A – A for cosine signals and

b = B – B for sine signals

Safe state

Phasor length "r" outside of the range

350 mV ≤ r ≤ 700 mV

Terminating resistor between A and A or B and B

120 Ω ±10%

Terminating resistor between A, A, B, B to the supply voltage and reference ground

> 1 kΩ

Sampling frequency

For the frequency maximally occurring in the application at the encoder signal outputs, the following sampling frequency must be met:

  • minimum 8 times with synchronous sampling
  • minimum 5 times with asynchronous sampling

The risk of an undetected fault at the safety encoder is increased if the sampling frequency is not adhered to. If you cannot adhere to the required sampling frequency when using the evaluation electronics, contact the manufacturer of the evaluation electronics to clarify any additional diagnostics.

If the safety encoders are operated with prefabricated encoder cables from SEW‑EURODRIVE on evaluation electronics from SEW‑EURODRIVE, these previously mentioned requirements have been met.