Installation
RES-403
Page 15
5.11.3 Configuration of the alarm relay
If the plug-jumper is not inserted - or if it is
incorrectly inserted - an error message
appears when the controller is switched on
(
ª
section 6.12 "Error messages" on page 26).
If the "Alarm output opened by alarm/PC CONFIGURA-
TION" position is selected (as of October 2005), the
behavior of the alarm output can be configured in more
detail by means of the ROPEX visualization software
(
ª
see section 6.10 "Diagnostic interface/visualization
software (as of October 2005)" on page 25).
5.12
Replacing and "burning in" the
heatsealing band
5.12.1 "Burning in" the heatsealing band
The heatsealing band is a key component in the control
loop, since it is both a heating element and a sensor.
The geometry of the heatsealing band is too complex to
be discussed at length here. We shall therefore only
refer to a few of the most important physical and elec-
trical properties:
The measuring principle applied for this system neces-
sitates a heatsealing band alloy with a suitable tempe-
rature coefficient TCR. Too low a TCR leads to oscilla-
tion or uncontrolled heating.
When heatsealing bands with a higher TCR are used,
the controller must be calibrated for this.
The first time the heatsealing band is heated to appro-
ximately 200…250°C, the standard alloy undergoes a
once-only resistance change (burn-in effect). The cold
resistance of the heatsealing band is reduced by appro-
ximately 2…3%. However, this at first glance slight
resistance change results in a zero point error of
20…30°C. The zero point must therefore be corrected
after a few heating cycles, i.e. the AUTOCAL function
must be repeated.
The burn-in effect described here does not occur if the
heatsealing band has already been thermally pre-
treated by the manufacturer.
An overheated or burned-out heatsealing
band must no longer be used because the
TCR has been altered irreversibly.
One very important design feature is the copper or
silver-plating of the heatsealing band ends. Cold ends
allow the temperature to be controlled accurately and
increase the life of the teflon coating and the heatse-
aling band.
0
5
1
2
3
4
6
7
8
9
Alarm relay contact
opened by alarm/
PC-CONFIGURATION.
Alarm relay contact
closed by alarm.
(factory setting)
CONFIGURATION
ALARM OUTPUT
DE-ENERGIZED / PC
AT ALARM
ENERGIZED
!
!