In-rush simulation function of the AEL series AC electronic load provides a test solution
for current components
The AEL series AC electronic load simulates the in-rush current function when electronic equipment is turned on, including
(1) The resistive load can simulate the current waveform change (either increasing or decreasing) when the power is turned on. In the display below, the blue on the top is the voltage waveform, and the red on the bottom is the current waveform.
(2) For rectified loads with transient current changes (either increasing or decreasing), a crest factor (ranging from 1.414 to 5.0) can be set to test and verify the performance of NTC (Negative Temperature Coefficient) or PTC (Positive Temperature Coefficient) resistors used to limit in-rush current.
The blue waveform on the top is the voltage waveform, and the bottom is the rectified load power waveform with a crest factor of 1.414.
The blue waveform on the top is the voltage waveform, and the bottom is the rectified load power waveform with a crest factor of 2.0 (3) Fuse/Breaker cycle testing up to 250 times (expandable to 99999 times) can determine Pass/Fail, providing test verification solutions for current control or protection components such as Fuse, Circuit Breaker, Switch, Relay, SSR, NTC, PTC, etc.
In the CR resistive mode of the AEL series AC electronic load, synchronization with the power signal is not required, making it suitable for all types of power waveforms, including sine waves, square waves, and stepped waves. It is also suitable for applications using phase control, such as SCRs and TRIACs. The constant current mode, however, requires synchronization with the power signal and is only applicable to AC power sources that provide a sine wave. The load current can be set with a crest factor ranging from 1.414 to 5.0. For application, first use a GPM digital power analyzer to measure the UUT's load current and crest factor, then input these data into the AEL series constant current mode's load current setting and crest factor setting. The AEL AC electronic load can then generate the UUT load current accordingly.
(5) Power system elaboration In an AC circuit, current flows from the power source to the load, and passes through control devices such as switches and relays, or semiconductor solid-state relays for ON/OFF control. For current protection, devices such as fuses and circuit breakers are used. The current then passes through components like NTC thermistors, rectifier diodes, filter capacitors, DC-DC converters, and finally reaches the load device.
Due to the practical difficulty of generating in-rush current during power-up, verifying current components can be challenging. This article introduces the use of the AEL series AC electronic load to simulate the current of load devices in the circuit (including both startup transients and steady-state operation) for testing and verifying components such as switches, fuses, circuit breakers (thermal, magnetic, or electronic types like SSRs), and current-limiting resistors.
The method for setting the startup in-rush current on the AEL series AC load is to first measure the worst condition of the power supply, that is, the in-rush current is the largest when the AC voltage source reaches the peak value, such as turning on the power supply at 90 degrees in the positive half cycle or 270 degrees in the negative half cycle. An oscilloscope can be used to measure the actual in-rush current peak value of the electronic device. This can be achieved using our 4016 power analyzer, which features a built-in load power switch that allows users to set the power-on phase angle to 90° or 270°. Based on the oscilloscope readings, such as the time it takes for the in-rush current to settle to a steady state, users can input these parameters into the AEL AC load's in-rush current mode. The AEL AC electronic load will then be able to simulate the in-rush current waveform as measured by the oscilloscope.
Power-on waveform of a resistive load at 90 Degrees Power-on waveform of a resistive load at 270 Degrees
Power-on waveform of a rectified load at 90 Degrees Power-on waveform of a rectified load at 270 Degrees
(6) NTC and PTC Testing: The load types in AC circuits include resistive loads, inductive loads, capacitive loads and rectified loads. Resistive loads, such as electric heaters, have a power factor of 1, which means they are purely resistive. There are two main types of thermistors, NTC and PTC.
NTC stands for Negative Temperature Coefficient, and the resistance of a thermistor decreases as the temperature increases. This type of resistor would be ideally suited as a series in-rush current limiter. Initially the resistance is high, then an in-rush current flows in and causes the thermistor's temperature to rise. After the in-rush current has risen, the resistance drops to a lower power loss level. Thereafter, when normal circuit current flows through the thermistor, the thermistor maintains a sufficiently high temperature level so that power losses can be kept low.
PTC refers to Positive Temperature Coefficient, meaning the resistance of this type of thermistor increases as the temperature rises. These components are commonly used as resettable fuses in series with the circuit. When the switching temperature is reached, the resistance rapidly increases, effectively limiting current flow. This makes PTC thermistors well-suited for overcurrent protection applications.
Since thermistors with a positive or negative temperature coefficient require actual current for testing and verification, the in-rush simulation function of the AEL AC electronic load in resistive load mode can be used to validate all current-related components within a resistive load, including NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient) thermistors to ensure they meet the circuit's design and performance requirements.
Rectified loads are commonly found in electronic products. Most electronic devices use a circuit that rectifies AC power using diodes, filters it with capacitors, and then converts it through a transformer or converter to provide the required DC power. Any circuit that includes diodes and capacitors for rectification and filtering is considered a rectified load.
When the voltage is a 50/60 Hz sine wave, the current waveform of a rectified load is typically a pulsed waveform that is roughly in phase with the voltage. The in-rush simulation function of the AEL series AC electronic load can be used to verify all current-related components within a rectified load, ensuring they meet the requirements of the circuit design.
U IEC 508/99 Current waveform on Vc (CH2, 4) AEL simulated current waveform
(7) Fuse / breaker cycling test elaboration: When the current control components mentioned above need to be evaluated for life cycle reliability or consistency, multiple and long-term tests are required. In addition to the aforementioned single in-rush current test, the AEL AC electronic load also provides a cycle test function of up to 250 times (expandable to 99999 times). The test results include a PASS or Fail judgment and the number of test cycles.
Voltage: 110V, cycle count set to 10 times. Test result: Fail (Trip test did not blow the fuse).
Voltage: 110V, cycle count set to 10 times, test duration 1 second. Test result: Fail (Trip test did not blow the fuse).
Voltage: 110V, cycle count set to 10 times. Test result: PASS (Trip test caused fuse to blow 2 times).
Voltage: 110V, cycle count set to 10 times, test duration 1 second. Test result: PASS (Trip test caused fuse to blow at 0.9 seconds).
Test waveform for 110V with 10 cycles
1. Test Setting Press the Item key to enter Test Setting
2. Fuse Test Press the Setting key to enter Fuse Test
2-1 Set the following parameters
a. Turbo mode OFF (ON: load time 0.1 second to 1 second)
b. Load current setting 5 A (can be expanded to 3-stage load)
c. Test time 1.0 second (can be set from 0.1 to 9999.9 seconds. When expanded to 3-stage load, each stage load time can be set from 0.1 to 333.33 seconds)
PS. After the expansion function, the test interval time is increased, and the interval time can be set from 0.1 to 9999.9 seconds.
d. The number of cycles is 10 times (can be set to 250 times, and can be expanded to 99999 times)
e. Test mode Trip (Trip/NTrip can be set)
3. Press START on the first display of Fuse Test to start the test.
4. Cycle test results
4-1 PASS display: Cycle number 002, test time 0.9 seconds
4-2 FAIL display: Cycle number 010, test time 1 second
5. Press the STOP key to stop the test.
Overseas Sales Department
Good Will Instrument Co., Ltd
No. 7-1, Jhongsing Road, Tucheng Dist.,
New Taipei City 23678, Taiwan R.O.C.
Email: marketing@goodwill.com.tw