West Control Solutions KS 800 Operating Instructions - Manual (Page 15)

Multi-Temperature-Controller KS 800
5.3 Resistance thermometer (IN1+/IN1-/IPT1 ... IN8+/IN8-/IPT8)
Pt 100, 2 or 3-wire connection
Resistance thermometer type PT 100 to DIN/IEC 751 can be connected in 2 or 3-wire circuit. The
max. measuring range is -100,0 ... 850,0
°
C, temperature-linear.
Connection in 3-wire circuit is possible without lead resistance adjustment, provided that the cross-
section of the individual wires is identical.
With 2-wire connection, a compensating resistor corresponding to the lead resistance must be fitted.
Using 2-wire connection is not recommendable.
The sensor is monitored for short circuit or break. The action (upscale/downscale) is configurable.
Resistance
wInstead of Pt10, a linearly variable resistor can be connected as a signal source in 3-wire circuit (
for connection, see section 7.1), 2-wire connection is not possible.
The max. resistance can be 400
Ω
. The measuring range starts at 0
Ω
to the final resistance value
(max. 400
Ω
) The output action is reversible by connecting the wiper either to IN+ or IN- .
Monitoring is only for lead break.
5.4 Screening
For compliance with the regulations on electromagnetic compatibility to EN 50082-2, the connecting
cables must be screened. The 2 screening possibilities are:
1. Each input is provided with a grounded screen connecting terminal to which the cable
screening must be connected. These interconnected screenings must be connected to the
ground potential (protective earth) via terminal 108 by means of the shortest possible cable
(approx. 20 cm).
2. Use a commercially available screen connecting system.
5.5 Heating current measurement and heating current alarm
KS 800 has an input for connection of an external current transformer. All heating loads connected
to a controller module are taken through a current transformer. Further processing and evaluation of
the transformer signal are in the multi-controller module.
Measurement principle: a KS 800 "control cycle" takes approx. 600 ms for all 8 controllers. Heating
current monitoring for a controller is possible after each 4th cycle, i.e. at intervals of 2,25 s. Via
software, this interval can be increased by a factor between 0 and 99 in common for all controllers,
whereby 0 means no monitoring.
E.g. factor 10: heating current monitoring for controller 1 is done after 22,5 s. After another 22,5 s,
the heating current of controller 2 is monitored, etc., i.e. controller 1 is monitored again after 9 x
22,5 s = 202,5 s
≈
3,5 min. Monitoring switch-off for individual controllers does not affect the cycle
time.
As all controllers except the one to be monitored are switched off during monitoring (which is swit-
ched on independently of its control status), the control accuracy can be affected negatively. There-
fore, heating current monitoring should be done only as frequently as necessary rather than as
frequently as possible.
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