CCT 31.3 I - Universal current transformer AC/DC
| measuring range | 0…300 A DC / AC Ieff, depending on variant! (rated current ranges set to standard values acc. to IEC) |
| Current output with AC input signal: | AC: 0…20 mA Ieff, (± 28,2843 mA IPeak) |
| Current output with DC input signal | DC: 0…± 20 mA |
| Max. burden resistance at current output | RB ≤ 300 Ω (UH = 24 V DC) |
| Output signal limitation in case of overload | < 25 mA |
| Accuracy | ± 0,5 % |
| Max. operating voltage Um | 0,72 kV, Ueff |
| Insulation test voltage | 6,4 kV, Ueff, 50 Hz, 5 sec., primary conductor against measuring output/housing |
| auxiliary voltage | ± 12 V DC, ± 15%, < 70 mA, external protection via fine fuse 100 mA / 250 V, fast! |
| Step response time (90 % IPN, di/dt = 100 A / μs) | ≤ 1 μs (typ. 150 ns) |
| Signal rise rate di/dt | < 100 A / μs |
| Insulating material class | E |
| Operating altitude | ≤ 2000 m (DIN EN 61010-1) |
| Max. temperature of the primary conductor | 100° C |
| Humidity | 0…95% rel. humidity, no condensation! |
Current transformer for measuring both direct and alternating currents
- For use in network analysis
- and for current measurement of non-sinusoidal and distorted networks
Applied technical standards:
DIN EN 50178, 1997
DIN EN 61010-1, 2002
VDE 0160
Electrical connections:
UH + 0 (Ground) IA
Spring-loaded terminal
Connection cross-sections: 0,08…2,5 mm²
Functions of the CCT 31.3 I:
- The magnetic field surrounding a current-carrying conductor is detected by a measuring core enclosing the conductor. The magnetic flux induced in the measuring core, which is directly proportional to the current in the primary conductor, is detected by means of a semiconductor component. Control electronics integrated in the device convert the signal supplied by the semiconductor into an output current signal that is directly proportional to the time profile of the measured variable.
- The inductive, contactless detection of the measured variable provides a galvanically isolated output signal.
- The electrical contacting of the secondary circuit of the current transformer is carried out via a 4-pole spring-loaded terminal. This terminal is suitable for connecting flexible stranded wires up to 2,5 mm².
- A DC auxiliary power supply of ± 12 V is required to supply the control electronics. The auxiliary voltage inputs must be protected by a 100 mA / 250 V / F fine fuse.
Advantages and benefits of the CCT 31.3 I:
- Measurement of both direct and alternating currents possible with only one current transformer.
- Large frequency range from 0 Hz (DC)…100 kHz (AC).
- High electrical safety due to galvanically isolated detection of the measured variable.
- Low power requirement (≤ 2,5 VA)
- Simple and safe electrical wiring using spring-loaded terminal technology.
- Direct mounting on busbars via mounting screws integrated in the device.
- Mounting on 35 mm DIN rails possible using optional snap-on mounting.
- High climatic and mechanical resistance due to PU potting of all electrical components.
3D models and more files to each product can be found in our download area downloadarea
current transformer knowledge
Background knowledge on the selection, dimensioning and technical parameters of current transformers – prepared in a practical manner.
Read morecurrent transformer correctly select & dimension
Published on 10 July 2026 · Updated on 31 July 2026
The choice of the suitable current transformer depends on primary current, connection values and purpose of use. This guide leads step by step through the most important selection criteria.
Read moreAccuracy classes for current transformers explained
Published on 10 July 2026 · Updated on 31 July 2026
What do specifications like class 0,5 or 0,2s mean for a current transformer? An overview of the common accuracy classes and their areas of application.
Read moreStromwandler richtig anschließen
Published on 24 September 2026 · Updated on 25 September 2026
Ein Stromwandler misst nur dann richtig, wenn er in der richtigen Richtung eingebaut und sekundärseitig korrekt verdrahtet ist. Entscheidend sind drei Punkte: Die Primärklemme P1 (K) zeigt zur Einspeisung, die Sekundärkl…
Read moreCurrent transformer for photovoltaic systems
Published on 10 July 2026 · Updated on 31 July 2026
In current measurement in PV systems, current transformers are used for recording feed-in, reference and consumption currents. Here you will learn what to pay attention to when selecting and dimensioning.
Read more