Eurotherm Drives 590 DRV Digital, Руководство по эксплуатации продукта

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590 DRV Digital DC Drive Product Manual
App. M - 33
Appendix M Special Blocks and Application Notes
M
For dancer applications, the feedback signal should be connected to be more positive when the web is tight and less
positive when the web is slack. In this arrangement, dancer feedback will increase the speed when the web is slack.
The trim range value depends on the nature of the web. It needs to be greater for an extensible web than for an non-
extensible web. In addition, the extensible web requires a higher control loop gain which comes with the greater trim
range. If required, trim ranges for two different types of web can be selected by configuring an unused digital input to
set two different values of trim range (see Extensible/Non-extensible Webs, page M-37).
Tension
The tension in dancer applications is determined by the air pressure or weight loading on the dancer. The drive only
controls the dancer position.
Other Features
This section explains how to use the many features available in the SC configuration.
Draw
To select draw mode, set SETPOINT SUM 1:: RATIO 0 to 100 percent. The input at terminal A2, DRAW/RATIO,
sets the amount of draw by adjusting SETPOINT SUM 1:: RATIO 1. It is multiplied by the line speed, terminal A4,
and then added to the line speed to produce the speed demand.
Calibrating analog input 1 in CONFIGURE I/O sets the draw range. In draw mode, the draw range is normally set to
about -5 to +5 percent. To set a 5 percent range, set CONFIGURE I/O:: ANALOG INPUTS:: ANIN 1 (A2):: CALI-
BRATION to 0.0500. Then, +10 volts on terminal A2 pr5 percent draw and -10 volts produces -5 percent
draw.
Terminal A2 can also be limited by MAX VALUE and MIN VALUE, clamps, with defaults of +100 and -100 percent.
If a draw range of more than 100 percent is required, the clamps must be increased accordingly. The clamps can be set
to lower values if asymmetric draw is required. For positive draw only, limit the input at A2 to 0 to +10 volts.
Cascade Draw
When two or more draw sections follow in line after a master drive section, cascading their line speed references in-
stead of having each section following the master can be more useful. To cascade the speed references, connect the
total speed setpoint signal, terminal A8, from the first section to the line speed reference input, terminal A4, of the sec-
ond section. Similarly, take the second section's total speed setpoint into the line speed reference of the third section,
etc. This allows a change to the draw setting of the first section to be passed to following sections while maintaining
their relative speeds.
Figure M.25 - Draw