11TCON1: Tension Control, Type 1 (3)
11.1Introduction (3)
11.2Principle of TCON1 (4)
11.3Overview (Block diagram) (7)
11.4Functions (7)
11.4.1Control and status words, data transfer (9)
11.4.1.1Control words TCON1 (9)
11.4.1.1.1Control words LCO (9)
11.4.1.1.2Control words MRG (12)
11.4.1.2Status words TCON1 (16)
11.4.1.2.1Status words LCO (16)
11.4.1.2.2Status word MRG (19)
11.4.1.3Data transfer (21)
11.4.1.3.1Data reception (21)
11.4.1.3.2Data transmission (22)
11.4.2Tension setpoint: Absolute or relative (23)
11.4.3Hard core function for an upcoiler (24)
11.4.4Tension ramp generator (26)
11.4.5Actual tension (27)
11.4.6Tension setpoint of the nearby tension zone (30)
11.4.7Tension regulator (31)
11.4.8Precontrol of the tension regulator (32)
11.4.9Tension cascade (32)
11.4.10Speed-dependent tension correction (33)
11.4.11Tension build-up: applying tension (34)
11.4.12Delta_V: Overspeed signal to override the revolution regulator (35)
11.5Simulation TCON1 (36)
11.6Block diagram (37)
11.7Description of variables (39)
11.8Program structure (40)
11.9Program layout (42)
absolute relative
11.9.1FC1342: Data reception (42)
11.9.2FB271 – FB285: Calling in the regulator (42)
11.9.3FC1343: Sending data to LCO (43)
11TCON1: TENSION CONTROL, TYPE 1
11.1Introduction
In order to move a strip from a coil in one place (uncoil) to another, a controlled force must be applied to the strip. The value of the strip force depends on the process.
Examples:
If we move a strip from the first point to the next point, the strip force must be constant enough for the strip to stay centered between the guide rollers.
The force during upcoiling must have a certain value. This can be important during the subsequent processing of the coil.
In a furnace, the strip force must be correct. If  the force is too great, creases may result; if it is not constant within acceptable limits, there is a risk that the strip will not remain properly centered on the furnace rollers.
In terms of control technology, we have several options for controlling the strip force by way of  variable speed motors. We divide these options into two groups:
•TCON1: Torque-based tension control or regulation
•TCON2: Speed-based tension regulation
TCON1: Torque-based tension control or regulation:
The tension resulting in the strip is brought about by directly changing the torque (or the active current) of the drive motor. Applying more torque (or power) to a motor means that more force is applied to the driven roll; this roll must then ensure that this extra power is converted into a higher strip tension.
TCON2: Speed-based tension regulation:
The strip tension is brought about by ensuring that a speed difference exists between two driven points (rolls). Let us assume that the first point (roll) drives the strip at a constant speed. Then we can, by controlling the speed of the second point (roll), change the force in the strip. By slightly increasing the speed, greater pull is exerted on the strip, with the result that the strip tension increas
es.
This chapter deals with the TCON1 regulation.
11.2 Principle of TCON1
The tension resulting in the strip is brought about by directly  changing the  torque (or the active current) of the drive motor.
The torque can be both controlled  and regulated .
T C O N 1 P r i n c i p l e
1
Controlled tension
If we ignore losses (power outputs of motors or gear boxes, losses due to friction or bending of the strip), we find a direct relation between the torque of a motor and the strip tension.
i
Diam Tension motor TQ ××=
2_
TQ_motor:  Motor torque [Nm] Tension: Strip force [N] Diam: Roll diameter [m] i:  Gear ratio, gearbox ratio []
The motor torque can be controlled in the following ways:
• We equip the motor with current or torque control.  We do not need a revolution controller. This
method is not commonly used. Reason: The motor will no longer be under control if slip occurs between the roll and the strip.
• We override the revolution controller (via a delta_V) so that we can directly control the torque
limits to the revolution controller.  This is the method commonly used.
Besides the direct relation, all losses, such as friction, bending and inertia losses, must be compensated.
Advantages:
• There is a simple and proportional relation between the theoretical calculation of the strip force and
the motor torque.
• No external tension load cell is needed (cost price, annual calibration etc.)
Disadvantages:
•    A fault in the tension of an upstream zone will be passed on to another tension zone unreduced. If
tension variations occur in a particular zone, these will be present in the nearby zones as well. We have no clean separation between the different tension zones.
• The strip tension will never correspond exactly to the actual tension (calculation errors).
• All losses in the strip must be calculated extremely accurately. Such losses will include frictional
losses, which are not always constant (function of temperature, speed, etc), or the bending losses, which are difficult to determine for greater strip thicknesses.
• In the case of speed changes, the inertia losses of all rolls must be compensated. This will cause
calculation errors in any case.
Applications:
• Downcoiler:  It is often difficult to place a load cell, or the accuracy of the tension may lie between
certain limits (e.g. + 5% accuracy band).
•    A zone between two bridles that does not have a load cell and where calculating the tension is too
difficult or inaccurate.

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