AC Loads

AC Electronic Load H&H ACL Series (Single-phase/Three-phase)

The H&H ACL series AC electronic load is suitable for AC and DC voltages up to 1kHz. It includes single-phase models as well as three-phase loads. The 4.3″ touchscreen simplifies operation, allowing users to directly define various waveforms, including phase angles and crest factors of harmonic and arbitrary current waveforms. The phase shift between load current and voltage can be combined with crest factor or phase angle control. Measurements for all channels/phases can be displayed digitally or as time-varying graphs similar to an oscilloscope. Even with changes in the crest factor, automatic amplitude correction ensures the RMS current value remains constant.

Key Features:

Frequency range up to 1kHz (DC, 40 … 1kHz)
Available as single-phase and three-phase models, with voltage options of 280V or 500V
Single-phase power: 500 W to 21,000 W
Three-phase total power up to 25.2kW (single unit)
Supports parallel, star, or delta connections
Operating modes: CC, CV, CP, CR
Arbitrary current waveform with seamless transitions
Adjustable phase angle from -180° to +180°
Adjustable crest factor up to 4
Combines adjustable phase offset with crest factor
Harmonics up to the 25th order, including even and odd harmonics
List operation, also compatible with three-phase currents
Standard interfaces: LAN, USB, RS-232, optional GPIB
Analog I/O port with optional real-time signal control
Comprehensive protection mechanisms: OCP, OVP, OPP, OTP
Multifunctional PC software – AC Tool

Highly Flexible Load Connection Design and Applications

The ACLT series includes the single-channel AC load (ACLS) and the three-phase load in the ACLT series. This design effectively integrates three AC load channels into a single enclosure. Depending on the specific application, the system can be configured as follows:

The three channels of the three-phase load can be used to operate three different DUTs (Devices Under Test) under AC or DC modes, or to test three-phase systems.
In balanced mode, all channels are set to load with the same settings and waveform.
In mains synchronization mode, Channel A synchronizes with the utility mains voltage, while Channels B and C have a 120° phase shift each.
To increase the maximum load current, two or three ACLT three-phase units or up to three ACLS single-phase units can be connected in parallel.

Loading Waveform Generation

Crest Factor

For a sine waveform, the crest factor (CF) can be adjusted between 1.4142 and 4.0. The amplitude resulting from load correction keeps the RMS value constant.

Phase cut/shift

For each waveform, the current waveform's phase cut and phase shift can be set within a range of -180° to +180°. The RMS value of the current changes according to the phase angle. Phase shift must be combined with either phase cut or peak factor. A phase shift in the sense of purely capacitive or inductive loads is not feasible.

Harmonics

In a waveform containing harmonics, the normalized fundamental amplitude from 0 to 1 is summed together with up to 24 harmonics (both even and odd). Load compensation ensures that the RMS value remains constant.

Arbitrary Waveforms

For a sine waveform, the crest factor (CF) can be adjusted between 1.4142 and 4.0. The amplitude generated by load correction keeps the RMS value constant.

Rectangular Function

Each cycle consists of 360 points, ensuring maximum waveform flexibility. The base signal can be a sine wave, square wave, or triangular wave, which can then be modified point by point. Depending on the waveform, the RMS value of the current will change.

DAQ - Data storage

The programmable four-quadrant power supply can synchronize the storage of data such as voltage and current over time and mark it at defined intervals. The buffer can store up to 40,000 data records, which can be read through a data interface and transferred to a USB flash drive. For storage intervals in the range of seconds, data can also be directly saved to the USB flash drive.