The Application of Ultra-High-Speed Electronic Loads in Current Sensor Response Time Testing

Current sensors are detection devices that use magnetic materials to sense the measured current and convert it into a standardized output according to a specific law (typically a linear relationship). Currently, electromagnetic sensors are widely used in automotive manufacturing, renewable energy generation, military aerospace, rail transportation, and other fields.

Response time is one of the critical performance indicators for sensors. It refers to the time difference between the output signal (secondary current, Is) and the input signal (primary current, Ip) during the rise phase—i.e., the delay between the output signal's rise time and the actual signal's rise. This parameter is particularly important for current sensors. Therefore, manufacturers and third-party testing institutions include response time testing in both type tests and routine tests.

Testing Requirements

Taking the standard TB/T 2763-2009 (Current and Voltage Sensors for Railway Vehicles) as an example, for closed-loop Hall current sensors, the standard specifies that the response time must meet the following thresholds: 1 µs, 3 µs, 15 µs, 20 µs, 50 µs, 100 µs.

Since the response time of current sensors is typically in the microsecond (µs) range, the testing equipment must have rapid current output capabilities. The test principle is illustrated below:

A high-speed signal source, composed of a high-current DC power supply and a high-speed electronic load, inputs a signal with an amplitude equal to the sensor's rated current value to the device under test (DUT). The signal's rise slope must satisfy di/dt > 50 A/µs, and the amplitude must remain stable after reaching the rated value (see figure below).

The response time is measured as the time difference (t2 - t1) between the moments when the output signal and the input signal reach 90% of their amplitudes, as recorded by an oscilloscope. The oscilloscope must have dual channels, and its timebase accuracy should be no less than ±5% to ensure precise waveform measurement.

Actual Test Waveform

The N67000 Series of high-speed programmable DC electronic loads achieves ultra-fast current loading through optimized component selection and system loop design.The current rise slope reaches 100 A/µs at 580A, meeting the high-standard testing requirements for current sensor R&D and third-party certification.

The measured response time of a channel in a three-phase current sensor of a well-known brand in the industry is as follows (387ns):

The N67000 Series is a high-reliability, high-precision, and multifunctional high-speed programmable DC electronic load. It offers three power specifications: 600W, 1200W, and 1800W, with a 1.8kW power density in a standard 19-inch 2U chassis. It supports master-slave parallel control for power expansion.

1. Ultra-High-Speed Current Loading: 60 A/µs

Single-unit current loading speed: 60 A/µs

Multi-unit parallel loading slope: >100 A/µs

Ideal for testing current sensors, AI chips, and high-speed switching power supplies.

2. Full-Parameter Three-Range Measurement: V/I/R/W

Supports constant voltage (CV), constant current (CC), constant resistance (CR), and constant power (CP) modes.

Ensures high-precision measurements across a wide range (1%–100%), suitable for current sensor accuracy and linearity testing.

3. Ultra-Low Operating Voltage: 0.7V @ 360A

The N67000 Series can operate at 0.7V under a 360A load, making it ideal for testing scenarios such as AI server power supplies and advanced CPU core power transient response analysis.

This capability allows engineers to evaluate chip performance under rapid load changes by observing voltage transients.