Installation
Page 20 RES-403
8.11.3 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
ªª
ª section 9.12 "Error messages" on page 31).
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 9.10 "Diagnostic interface/visualization
software (as of October 2005)" on page 30).
8.12 Replacing and "burning in" the
heatsealing band
8.12.1 "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 pret-
reated 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 heat-
sealing 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
!
!
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