Speed Profile; Critical Speed Avoidance; Polarity Control; Speed Ramp - Siemens 6SR41 series Product User Manual

Application and Operation
6.5 Command Generator
Set Point Sources
Set Points are internal menu entries that are static values based on user entry, keypad
settings, or remote demand from a network communication interface. There are a total of
eight inputs that are menu entries from remote communications. There are two special
additional entries that are reserved for safety override and jog level set points.
● Keypad
● Increment/Decrement (Sample and Hold)
● Increment/Decrement Step
● Preset levels
● Jog
● Communication Network
6.5.2

Speed Profile

The Speed Profile uses the velocity demand signal as input, and generates a modified Best
Fit Straight Line (BFSL) velocity demand output.
6.5.3

Critical Speed Avoidance

Critical speed avoidance is used to prohibit the drive from operating in frequency ranges that
may cause resonant frequencies in mechanical systems. The NXG control provides three
independent avoidance bands.
6.5.4

Polarity Control

Polarity control is simply an inverter. The output of the polarity block is the opposite polarity
of the input. The selection of this feature is based solely on the system program logic.
6.5.5

Speed Ramp

The Speed ramp is a functional block that takes an input demand and generates an output
with a controlled rate of change, based on the acceleration and deceleration limits
120
– Front panel keypad (or ToolSuite computer) used to set speed demand
– Digital inputs (x2) that increase/decrease raw speed demand at the active
acceleration/deceleration rate, while input is maintained
– Digital Inputs (x6) that provide programmable step change to output demand each
time input transitions from Low to High state
– Multiple user-defined preset values via menu system
– Set to maximum active speed limit, intended for test purposes to "bump" motor
– Digital Value as set per external communication interface to a PLC/DCS
Operating Instructions, Version AE 12/2009, A5E01454341C
Product User Manual