advanced line
GENERAL
The microprocessor-controlled KS 800
ensures precise, low-cost multi-loop
control of temperature, and features an
interface for bus or field-bus. Standard
functions such as “set-point lowering”
and “heating/cooling with four alarms”
make the KS 800 ideally suited for temperature
control of plastics processing
machines, heated moulds, packaging
machines, tempering units, and other
similar thermal processes.
Furthermore, with high-power heating
elements (e.g. in hot-runner moulds),
the selectable functions “output hold ”in
case of sensor break, and “start-up circuit
”ensure increased element life and
prevent interruptions during Production.
The self-tuning feature guarantees very
short start-up times.
For implementing continuous and
split-range controllers, the KS 800 can
be fitted with 8 additional analog control
outputs.
DESCRIPTION
The following description is based on
the fact that every one of the 8 control
loops contains a completely independent
controller.
Input circuit monitoring
Incase of a fault in sensor or leads, the
built-in monitor provides increased operational
safety. The controller output action
after monitor triggering can be configured
for:
downscale (min. output)
upscale (max. output)
outputs switched off
switch-over to average output value
Thermocouple input
The monitor is triggered by wrong
sensor polarity or TC break.
Resistive input
The input is monitored for a break or a
short circuit in the sensor and leads.
Measurement value correction for
thermocouples, Pt 100, linear input
The correcting function is used to
change or scale he measurement value.
It can be applied either for zero offset
(b)or for gain adjustment (m), or both, according
o he equation “mx +b ”. For
this, the controller computes the values
for m and b from two input values (x1in,
x2in)and two set-points (x1out, x2out).
Easy calibration is possible online via an
operating page of the engineering tool.
Heating current monitoring and alarm
The KS 800 has an input for an external
current transformer, whereby rectification
of the input signal is done on board.
All the connected heating leads of the
KS 800 ’s controllers are passed through
the current transformer.
If the monitoring function has been activated,
the heating outputs of all the control
loops are switched on briefly in succession,
and the heating current is measured.
If the measured current is lower
than a defined limit value, this information
can be signalled to one of the alarm
outputs or transmitted via the field bus.
Similarly, the heating output can be monitored
for a short-circuited actuator
(SSR).In this case, the heating current is
measured when the heating output is
switched off. If the measured current exceeds
3% of the selected range, an
alarm is triggered.
In addition to checking for exceeded
heating current limits, the actuator (solid
state relays) is checked for short circuit.
With the outputs switched off, the heating
current must not exceed 1,5% of the
selected heating current measuring
range. With detected errors, the relevant
channel number is also output by KS
800.
Leakage current monitoring
Heating elements with a high leakage
current (e.g. due to penetrated moisture)
are detected by this circuit.
Monitoring is carried out with the heating
output switched off. An external current
relay monitors the difference between
the phase currents and the current
in the neutral lead. If the difference
exceeds a pre-defined value of 10...100
mA, the system transmits a 24 V DC
alarm signal to the controller module.
Through cyclical activation of the heating
circuits and corresponding scanning, a
single current relay can be used for all 8
KS 800
Multiple
temperature controller
8-channel controller in housing for rail mounting
CAN/ CANopen, PROFIBUS-DP, DeviceNet, RS 485/422
Connection of Engineering Tool or local operation
Self-Tuning to the setpoint without oscillation
Automatic start-up circuit
Switch-over to output “hold ”on sensor break
Monitoring for heating current and actuator
3 configurable alarm outputs or relays
8 analog outputs (option)
Direct connection of melt pressure sensors (option)
PMA
