- General Electric Computer Accessories User Manual

3-94 •
••
• Chapter 3 Paramters/Functions Innovation Series Medium Voltage GP Type - G Drives GEH-6385
After the speed reference has been selected from the local or remote source, the
Speed Reference Generation function allows several subordinate functions to operate
on the speed reference. The Speed Reference Reverse function reverses the speed
reference if the user has requested that action. The Minimum Speed Limit function
makes sure the speed reference magnitude is above a specified level. The Critical
Speed Avoidance function prohibits the speed reference from entering specified
ranges. The Speed Reference Ramp function limits the speed reference’s rate of
change.
The output of the Speed Reference Ramp function (Speed ref, ramped) is also the
output of the Speed Reference Generation function. This final speed reference passes
to the Speed/Torque Overview function for further conditioning before it becomes
the reference to the Speed/Torque Regulator function.
Related diagrams
• Speed Reference Generation (Ovr_RfSel)
Speed Reference Ramp
The Speed Reference Ramp function forces the speed reference to change in a
controlled fashion. It limits the rate of change of the speed reference that goes to the
Speed/Torque Overview function.
Function inputs
The following table specifies the input variables of the Speed Reference Ramp
function.
Variable Description
Speed ref, pre ramp
Speed reference that is the output of the Critical Speed
Avoidance function (variable Spd avd func output). RPM
Speed reg fbk
Speed feedback that in some conditions becomes the
output of the ramp. RPM
Ramp ref enabled Enables the speed reference input to the ramp.
Emergency stop act A Stopping Commands and Modes signal that indicates
that an emergency stop has been commanded.
Function outputs
The following table specifies the output variables of the Speed Reference Ramp
function.
Variable Description
Speed ref, ramped
Speed reference which has been rate limited by the linear
ramp. RPM
Function configuration
The following table specifies the general configuration parameters of the Speed
Reference Ramp function.
Parameter Description
Ramp bypass Disables the Speed Reference Ramp function.
Ramp rate mode Specifies whether the speed independent ramp rate mode or
the programmed ramp rate mode is active.
Emerg ramp rate Deceleration ramp rate under emergency stop conditions.
RPM/second