Specifications

Control Block Description ADDvantage-32 PLUS
4-116
This block selects the type of speed feedback to be used by the speed loop. Either CEMF
or speed feedback may be employed. When tach feedback is selected, tach loss detection
can be used by configuring Y***:USR FAULT 1 = TACH LOSS.
This block also has the option of using redundant tach inputs. On a tach loss of the
primary tach, it can be specified to switch to a second tach feedback while still running
the drive. If the tachs fail, CEMF feedback can be selected for the speed feedback. The
tach inputs can be configured to either analog or digital feedbacks.
1. Inputs
TACH1: Analog
TACH2: Analog
CEMF: Analog
MXSPD: Analog
GAIN: Analog
SPDVOL: Bit
1 OR 2: Bit
V RED: Bit
RED: Bit
RES: Bit
2. Outputs
OUT: Analog
1WARN: Bit
2WARN: Bit
TL: Bit
3. Implementation
The speed output of the TACH SELECT block is selected from CEMF, TACH1, or
TACH2 inputs, and scaled by the GAIN input. In order to work properly, the CEMF,
TACH1, and TACH2 inputs need to be properly scaled into the appropriate units. If
TACH feedback is scaled in FPM or other process units, the motor’s CEMF input will
need to be scaled into the identical units. Note: If frequency inputs are used as TACH
input, Section III gives details on how the scaling parameters need to be set in order to
get the proper units. The GAIN input can be used to scale all inputs into process units
that will match the Speed Reference. Typical operation of the TACH SELECT block is
described below.