Setting The Measuring Time To Evaluate Speed "0; Sliding Averaging Of The Speed Actual Value - Siemens SINAMICS S120 Function Manual

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Further information on the procedure

● For the 4x evaluation, both the rising and falling edges of a contiguous pulse pair on the A

and B tracks are evaluated.

● For the 1x evaluation, only the first or the last edge of a contiguous pulse pair on the A and

B tracks are evaluated.

● A 4x evaluation of the pulse encoder signals allows a minimum speed to be detected which

is a factor of 4 lower than for the 1x evaluation. For incremental encoders with uneven pulse

duty factor of the encoder signals or where the encoder signals are not precisely offset by

90°, a 4x evaluation can result in an actual speed value that is somewhat less steady.

● The following formula defines the lowest speed where a distinction can be made to 0:

n_min = 60 / (x*p0408) [rpm]

with x = 1 or 4 (x times evaluation)

You can only use the reduction to 1x evaluation in conjunction with the edge zero mark or

without zero mark. Detection with an accuracy of one pulse is no longer possible for zero marks

with "unambiguous range" or distance-coded zero marks.

Setting the measuring time to evaluate speed "0"

The function is only necessary for slow-speed drives (up to 40 rpm rated speed) in order to be

able to output actual speeds correctly close to "0". For a stationary drive, this prevents that the

I component of the speed controller slowly increases and the drive unnecessarily establishes

Commissioning the function

Enter the required measuring time in parameter p0453. A speed actual value of "0" is output,

if, within this time, no pulses are detected from the A/B track.

For slow-speed drives (< 40 rpm), when using standard encoders with a pulse number of 1024,

a problem is encountered due to the fact that the same number of encoder pulses is not

available for every current controller cycle (for p0430.20 = 1: Speed calculation without

extrapolation, "Incremental difference"). The different number of encoder pulses means that

the speed actual value display jumps, although the encoder itself is rotating at a constant

Drive functions

Function Manual, 06/2019, 6SL3097-5AB00-0BP2

Basic functions

8.21 Tolerant encoder monitoring