Ssm Function - ABB ACS880 User Manual

This time scheme diagram illustrates the operation of the SMS function (version 1).
Motor speed
A Safety function response time
B SMS trip limit positive (parameter SMS.14)
C SMS trip limit negative (parameter SMS.13)
D Time to zero speed: Time from the STO activation to the moment when the acknowledgment be-
comes allowed (parameter STO.14). You must set this to the estimated time in which the motor
coasts to a stop from the maximum speed.
1. The motor speed reaches the SMS trip limit positive.
2. After the safety function response time (A), the FSO module activates the SSE function,
which activates the inverter unit STO. The motor coasts to a stop. In this case, the SSE
function is configured as Immediate STO (parameter SSE.13).
3. After time (D) has elapsed, the FSO module automatically acknowledges the SSE
function (parameter STO.02 is set to Automatic) and deactivates the inverter unit STO.
The user must reset the inverter unit if the STO indication parameter (FSOGEN.62 or
31.22) is set so that a fault is generated.

SSM function

￭
Note: Only the FSO-21 module supports the SSM function.
Safe speed monitoring (SSM) provides a safe output signal to indicate whether the motor
speed is between user-defined limits. When the motor speed is within the SSM limits, the
SSM indication signal in the FSO module is on.
There are four separate SSM functions in the FSO module with different parameter settings.
The SSM1 function is used as an example and in the delivered default settings of the +Q966
option. ABB activates the SSM1 function at the factory. The user sets the SSM positive and
negative speed limits at the start-up. For more information, refer to chapter
settings and the FSO module user's manual.
A
STO.14
D
1
2
Option description 27
B
Time
3
C
Inverter STO status
SSE status
Parameter