Electronic Current-Transducer Type STWA1FH
AC Electronic current transformer with freqency output
The STWA1FH provides a frequency output with 0.5...20 Hz which corresponds to a current flow of AC 0 - 20 A through the transformer. Multiple loops of the conductor through the transformer reduce the current range correspondingly (e.g. with fourfold looping-through 0 - 5 A correspond to 0.5...20 Hz).
For the monitoring of high currents, the STWA1FH is simply looped in the secondary circuit of a large current transformer. Consequently, the frequency output is proportional to the primary current of the transformer, e.g. 0 - 100 A for a transformer with 100/5 A (cable four times through the STWA1F).
The offset of 0.5 Hz at the beginning of the transducing range is for technical reasons. During evaluation, it can be taken into account.
Application: The STWA1FH enables moderately priced detection of the value of an AC-current with a DIGITAL INPUT of a PLC. Costly analogue inputs are no longer necessary.
The STWA1FH is particularly suitable to evaluate the current in electric motors in machines of i.e. saws. The feed can be regulated dependent from the load of the motor of the saw.
Overview of Functions
- current-proportional frequency output 0.5 - 20 Hz = AC 0 - 20 A
- output isolated, max DC 30 V/30 mA
- output frequency limited to 30 Hz
- output can be connected to the digital input of a PLC
- incorporated reverse voltage protection diode
- electrical connection via screwless pluggable terminals
- supply voltage DC 10...30 V
- DIN-rail-mount or with screws
- plug-in current transformer (Ø 11 mm)
- option: currents up to 60 A, other frequencies
Supply Voltage Us
DC 10 ... 30 V, max. 22 mA, typ . <13 mA
AC 0 ... 20 A
0,5 ... 20 Hz
max. DC 30 V
Switching current min/max
DC 1 mA / 30 mA
< 0,5 s.
Error (of scale, above 10%/Irated)
≤ 3 % v.E.
Nominal frequency / operating range
50/ 50...400 Hz
Overload capacity cont./10s
IN+5% /200 A
Testing voltage to supply voltage
max. ambient temperature
Dimensions (h x w x d)
50 x 36 x 56 mm
Diameter for conductor
ca. 90 g
FAQ / Product videos