West Control Solutions KS 800 Operating Instructions - Manual (Page 22)

Multi-Temperature-Controller KS 800
Note: Unless these alarm outputs are used as alarm outputs, they can also be used as digital
outputs of a control system (see also section 5.8).
6.4 Constant voltage and auxiliary relays
KS 800 version 9407 480 xx3xx is provided with a constant voltage source, which is galvanically
isolated from all other KS 800 inputs and outputs.
This constant voltage source can be used for energizing a strain-gauge bridge (pressure sensor).
Galvanic isolation permits direct connection of the bridge diagonal (bridge output) via a KS800 input
configured as a mV-input.
U = 10V
±
0,2%; Imax = 60mA
The constant voltage source is protected against short circuit without being permanently short circuit
proof.
Sensors used for pressure measurement are normally provided with a built-in resistor, which chan-
ges the bridge output signal by 80% if connected in parallel to a bridge arm.
Therefore, function checking is possible after de-pressurizing.
For connecting this resistor in parallel, this KS 800 version is fitted with an additional relay with
change-over contact, which can be controlled by applying an external voltage (24V= from a digital
system output card; current sink type1 to IEC 1131) or via the system bus.
The relay is designed for switching "dry circuits". For using the relay for this purpose, the switching
current must not exceed 2mA, to prevent an increase of the contact resistance (burning off or
oxydation due to spark formation), which leads to bridge output measurement errors.
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