Description
NK ATR1-420-24L-FT – Current Transducer, ATR Series

- Full scale range = 10, 20, 50 A
- Output signal = 4-20 mA
- Power supply = 24 VDC loop-powered (4-20 mA output ONLY)
- Case style = Solid-core, top terminals
ATR Series AC Current Transducers combine a current transformer and a True RMS signal conditioner into a single package. These current transducers provide True RMS output on distorted waveforms found on VFD or SCR outputs, and on linear loads in “noisy” power environments. The ATR Series AC Current Transducers are available in a solid- or split-core case.
Monitoring a Motor Driven with a VFD

Use the ATR current transducer on the line or load side of the drive and the signal will be accurate in either position.
AC Current Transducer Applications
VFD Controlled Loads
- Monitoring VFD output indicates how the motor and attached load are operating.
SCR Controlled Loads
- Accurate measurement of phase angle fired (time proportioned) SCRs.
- Current measurement gives faster response than temperature measurement.
Switching Power Supplies and Electronic Ballasts
- True RMS sensing is the most accurate way to measure power supply or ballast input power.
AC Current Transducer Features
True RMS Output
- True RMS technology is accurate on distorted waveforms like VFD or SCR outputs.
Jumper-selectable Ranges
- Reduces inventory.
- Eliminates zero and span pots.
Isolation
- Output is magnetically isolated from the input for safety.
- Eliminates insertion loss (voltage drop).
UL/cUL and CE Approved
- Accepted worldwide.
Selecting the right transducer:
The current waveforms of a typical linear load is a pure sine wave. In VFD and phase angle fired SCR applications, however, output waveforms are rough approximations of a sine wave. There are numerous spikes and dips in each cycle. ATR transducers use a mathematical algorithm called “True RMS”” which integrates the actual waveforms over time. The output is the amperage component of the true power (heating value) of the AC current waveforms. True RMS is the only way to accurately measure distorted AC waveforms. Select ATR transducers for nonlinear loads in “noisy” power environments.
AC Current Transducer Connections

4-20mA
AC Current Transducer Ordering Information
Sample Model Number: ATR1-420-24L-SP
True RMS AC current transducer, 10/20/50 A ranges, 4-20 mA output, 24 VDC loop-powered in a split-core case. (DIN rail adapters are included)
| (1) | (2) | (3) | (4) | |||||||||
| ATR | – | 4 | 2 | 0 | – | 2 | 4 | L | – | |||
| (1) Full Scale Range | |
| 0 | 2, 5 A |
| 1 | 10, 20, 50 A |
| 2 | 100, 150, 200 A |
| (2) Output Signal | |
| 420 | 4-20 mA |
| (3) Power Supply | |
| 24L | 24 VDC loop-powered (4-20 mA output ONLY) |
| (4) Case Style | |
| FT | Solid-core, top terminals |
| SP | Split-core |
Product General Attributes | |
|---|---|
| HTS/Schedule B Number | 8536.50.7000 |
| ECCN Number | EAR99 |
| Country of Origin | United States |






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