STW1K 10630-0710-00 page 4 / 6 www.ziehl.de
6 Detailed description
The STW1K current relay operates in an OR circuit and detects whether or not current is flowing in one of up
to 8 monitored wires. The relay is activated when the current flowing through the current transducer exceeds
a value of approximately 1 A. The output is a potential-free switching contact. It can be used to turn on
additional equipment such as extraction or blowing systems. If this value falls below approx. 0.5 A, the relay
switches off the auxiliary equipment again (after the switch-off delay time has elapsed). The STWA1(H)
current transformer can be loaded with a maximum current of 100 A.
Tips:
Response threshold is too high (current flow in the wire is too low):
wires pass through the current transformer STWA1(H) several times.
Response threshold is too low (base load current must be extinguished):
connect a resistor (0.25 W / 200 V) to the corresponding input of STW, in parallel to the current
transformer STWA1(H).
750 Ω resistor = increase by a factor 2
330 Ω resistor = increase by a factor 4
120 Ω resistor = increase by a factor 10
Due to large tolerances that must be considered, we recommend that the best values be
determined by trial and error method.
Length of connecting cables STWA1(H):
Up to 50 m, also much longer are also possible.
Shielding may be required when laid parallel to power lines.
7 Assembly
The unit can be mounted as follows:
mounting of the on a 35 mm mounting rail according to EN 60715
optional: M4 screw fitting, only with additional bolt (not included)
Make the connection in accordance with the wiring diagram or the nameplate
When installing the device into the switchgear cabinet, please observe the max.
admissible temperature. Care for both, sufficient clearance to other devices and
sources of heat or enough forced draught. If cooling is made more difficult, e.g. close
devices with increased surface temperature or by handicap of airflow cooling, the
permissible ambient temperature has to be reduced.
8 Start-up
Attention!
Only 1 live conductor may be fed through the current transformer!
switch on the mains voltage
when the device is ready for operation, the relay must switch on when a current ≥ approx.
1 A flows through the current transformer.
