When insulation systems, transformers, or cables are stressed with impulses, you don’t want guesswork; you want clarity. Enter the Haefely HiAS 744, a cutting-edge impulse analyzing system designed to capture, analyze, and make sense of high voltage phenomena with unmatched fidelity. Compact, versatile, and engineered for testing laboratory applications, the HiAS 744 is your ally in mastering the invisible world of electrical impulses.
What is the HiAS 744?
The HiAS 744 is a high voltage impulse analyzing system from Haefely, a company with over a century of expertise in high voltage testing. It captures lightning-type spikes, switching surges, and fast front impulses, recording them in extreme detail. Engineers and technicians can analyze these waveforms to evaluate insulation performance, detect distortions, and study subtle electrical phenomena that could affect reliability and safety.
A HiAS 744 for every application
The HiAS 744 lineup is offered in three models, each designed to match different performance needs.
HiAS 744 – Basic Version
Perfect for standard applications, the basic model delivers 11-bit amplitude resolution and ±1.5% peak voltage accuracy for both full and tail-chopped impulses.
HiAS 744-S – Standard Version
Stepping up in precision, the standard version offers 16-bit amplitude resolution and improves peak voltage accuracy to ±1.0% for full and tail-chopped impulses.
HiAS 744-REF – Reference Version
Built for the highest accuracy requirements, the reference model features 16-bit amplitude resolution with an exceptional ±0.7% peak voltage accuracy, making it ideal for reference measurements and demanding test environments.
Key highlights:
✅Up to 16-bit resolution with up to 250 MS/s sampling for precise waveform capture
✅Optically decoupled front-end, reducing ground loops and interference
✅Flexible input range: ±5 V to ±2000 V peak, compatible with a variety of voltage dividers
✅Supports 1 to 4 channels, allowing simultaneous measurement of multiple points
✅HiAS Software, which has been upgraded to suit the new hardware, retains the comfortable interface proven and tested by many hundreds of satisfied users, and continues to be compatible with the former versions of data files of the HiAS, allowing data comparison to older measurements.
This is a system that empowers users to capture the faintest whisper of a voltage spike, not just the obvious surge.
Setting Up the HiAS 744: Step by Step
Setting up the HiAS 744 correctly ensures accurate, repeatable results. Here’s how a high voltage lab typically deploys the system:
- Location & Mounting
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- Place the front-end digitizer close to the test field to minimize cable length and reduce signal distortion.
- Utilize the optically isolated fiber connection to the control PC in a safe, distant room. This isolation enhances safety and eliminates interference from high voltage sources.
- Ensure proper grounding: star-point grounding, low-inductive paths, and copper foil connections minimize noise in fast impulse measurements.
- Electrical Chain Configuration
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- Connect the impulse voltage divider or shunt to your test object.
- Attach the divider output to the HiAS input using the LEMO 4S connector.
- Enter the divider ratio or terminal value into the software to ensure correct scaling.
- Use shielded cables and verify terminations to avoid measurement errors.
- Software Configuration
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- Launch the HiAS software and create a new test database.
- Configure test headers: object, date, impulse shape, channels, and polarity.
- Define the impulse type: lightning, switching, or front-chopped.
- Trigger impulses via the generator; the HiAS captures waveforms, computes key parameters (T1, Tp, Tc, crest factor, etc.), and displays them with reference curves.
- Save and back up results; export raw data if additional analysis is needed.
- Calibration & Maintenance
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- Regular calibration using an impulse calibrator ensures measurement traceability.
- Perform self-tests to verify system health.
- Maintain inspection of cables, fiber links, and shielding to prevent measurement errors.
Common Problems the HiAS 744 Solves
High voltage impulse testing can be fraught with challenges. The HiAS 744 addresses them head-on:
✅Capturing fast impulses and chopped waves: Traditional systems often fail at high-speed transients. The HiAS records with exceptional accuracy.
✅Reducing interference and ground loops: Galvanic isolation and smart front-end placement provide clear, repeatable measurements.
✅Ensuring traceability and comparability: Legacy data compatibility allows trend analysis and quality monitoring.
✅Supporting multiple channels: Simultaneous measurement of voltage and current or multiple phases saves time and improves diagnostics.
✅Simplifying operations: Automated parameter extraction, zooming, and editing reduce operator error and enhance productivity.
✅Standards compliance: Meets IEC 60060‑2, IEC 61083‑1/2, IEEE Std 4, ensuring measurements are accurate and reliable.
Applications
The HiAS 744 is versatile across many high voltage testing scenarios:
✔️Impulse voltage testing: Transformers, bushings, switchgear (GIS and AIS)
✔️Impulse current testing: Surge arresters, protective devices
✔️Cable and conductor testing: AC and DC cables under high voltage conditions
✔️Research & diagnostics: Material and insulation testing requiring extreme precision
✔️Factory production tests: Fast, repeatable tests with clear traceability
HiAS 744 Quick Troubleshooting Guide
Insider Tips & Best Practices
✅Always back up your database and calibration files before major testing sessions.
✅Always verify divider ratios before running tests.
✅Keep fiber-optic connections clean to prevent signal degradation.
✅Split test databases to avoid long load times.
✅Perform frequent calibration for critical research or production measurements.
✅For labs testing high-frequency impulses, short cables and low-inductive grounding are key to accurate waveforms.
Why the HiAS 744 Matters
The Haefely HiAS 744 is a modern marvel in high voltage impulse testing: precise, flexible, and reliable. Think of it as a blueprint for high voltage insight. Just as you meticulously monitor, measure, and optimize health and energy in a natural living system, the HiAS 744 lets engineers peer into the electrical world, revealing the subtle stresses and distortions that would otherwise go unnoticed. It’s not just an instrument; it’s a tool for understanding, predicting, and optimizing performance in the most demanding electrical environments.