STW20K
12440-0702-03
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www.ziehl.de
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Detailed description
The current monitor STW20K detects whether one of max. three circuits is interrupted or no current flows.
The device works exclusively with current detection transformers type STWA1, STWA1H. This transformer
supplies a voltage signal of approx. 1.5 V at 1 A. This voltage is fed to a comparator in AND circuit. If voltage
is applied to all inputs, the built-in relay is switched on and the contacts 11, 14 and 21, 24 are closed. If an
input is without voltage, the relay switches off and the contacts 11, 12 and 21, 22 are closed, the led alarm
lights up red.
If the switching threshold is not reached at low currents below 1 A, the monitored conductor must be routed
through the transformer several times.
9.1 Tips:
Limit too high
(current in wire too low):
•
Loop through wire several times
Limit too low
(small loads shall not be recognized)
•
Connect a resistor (0,25 W / 200 V) in parallel to the current transformer STWA1(H)
➢
- - resistor 750 Ohm = enhancement by factor 2x
➢
- - resistor 330 Ohm = enhancement by factor 4x
➢
- - resistor 150 Ohm = enhancement by factor 10x
Because of high tolerances we recommend to determine the best value by try out.
10
Disposal
Disposal should be carried out properly and in an environmentally friendly manner in accordance with legal
provisions.
11
Error search
•
LED Power On is off
Make sure that supply voltage is connected correctly (+/-) to terminals A1/A2 and correspond with the
voltage on type plate.
•
Check that the current transformers are correctly connected and the terminal voltage is > AC 1.5V.
The load must be switched on.
•
Check that only 1 live conductor has passed through the converter. Only 1 conductor per converter
can be monitored.
See also
:“ under item Detailed description
