Eurotherm Drives 590 DRV Digital, Product Manual

Page: 135 / 318

Appendix C Setup Parameters
590 DRV Digital DC Drive Product Manual App. C - 28
C
STANDSTILL
STANDSTILL determines when the speed setpoint is zero and the motor has stopped.
Inputs and Outputs
The inputs are SPEED FEEDBACK from the speed loop and SPEED SETPOINT
from setpoints. The outputs are AT ZERO SPEED, AT STANDSTILL, and AT
ZERO SETPOINT. AT ZERO SPEED is connected to DIGITAL O/P 1, terminal B5,
in the default configuration. A "not at standstill" signal is sent to the drive enable
logic.
Description
When SPEED FEEDBACK is less than ZERO THRESHOLD, the AT ZERO SPEED
output is ON. AT ZERO SETPOINT is ON when SPEED SETPOINT is less than
ZERO THRESHOLD. When both AT ZERO SPEED and AT ZERO SETPOINT are
ON, AT STANDSTILL is ON signaling the motor has stopped.
DIGITAL DC DRIVE
MENU LEVEL
MENU LEVEL
DIAGNOSTICS
MENU LEVEL
SETUP PARAMETERS
SETUP PARAMETERS
RAMPS
SETUP PARAMETERS
SETPOINT SUM 1
SETUP PARAMETERS
STANDSTILL
M
M
When STANDSTILL LOGIC is ENABLED, the SCR firing circuits are disabled, the main contactor remains ener-
gized and the RUN LED stays on when the drive is at standstill. The drive remains in this state until standstill drops
out. That is, when the speed setpoint or speed feedback rise above the zero threshold.
STANDSTILL LOGIC is useful in maintaining absolute zero speed but can cause problems in web handling applica-
tions using tension feedback. At zero speed, the SCR's turn off allowing web tension to pull the driven roll in reverse.
Once the drive no longer senses it is at zero speed, the SCR's turn back on causing the motor to move forward and
regulate tension. An oscillation condition can result as the drive SCR's turn on and off trying to maintain a fixed
position.
Parameters
Tag Parameter Description Range Default
11 STANDSTILL LOGIC When enabled, inhibits the controller when at zero ENABLED/DISABLED DISABLED
setpoint and zero speed.
12 ZERO THRESHOLD Threshold for setting the zero setpoint and zero speed. 0.00 to 100.00% 2.00%
Controls the zero speed relay output.
Figure C.23 - Standstill