Combined Wave Generator Technical Guide: Principles, Applications, and the LISUN SG61000-5

Fundamentals of Surge Immunity Testing

Electrical and electronic systems are perpetually subjected to transient overvoltages, or surges, originating from both natural phenomena and operational switching events. These surges represent a significant threat to equipment reliability and longevity. Surge immunity testing, therefore, constitutes a critical component of electromagnetic compatibility (EMC) validation, designed to assess a device’s ability to withstand such high-energy disturbances without performance degradation or permanent damage. The combined wave generator is the specialized apparatus specified by international standards to simulate these real-world transient conditions in a controlled laboratory environment. The underlying principle involves generating a high-voltage impulse that is applied to the equipment under test (EUT) via power supply lines, communication ports, or signal lines, thereby verifying the efficacy of its internal protective circuitry and inherent insulation strength.

The test waveform itself is a composite signal, meticulously defined to emulate the characteristics of both lightning-induced and switching transients. It consists of a high-voltage, low-current component for open-circuit conditions and a high-current, lower-voltage component when the circuit is closed. This dual-nature waveform ensures that the test is representative of the surge’s behavior as it propagates from the point of origin, through cabling, and into the EUT’s impedance. The standardization of this waveform, as delineated in IEC 61000-4-5, ensures consistent and reproducible test results across different laboratories and product categories, forming a universal benchmark for surge immunity.

Anatomy of the Standard Combined Waveform

The technical definition of the combined waveform is precise and non-negotiable. According to IEC 61000-4-5 and related standards such as ISO 7637-2 for automotive applications, the waveform is characterized by two distinct but simultaneously delivered components: an open-circuit voltage wave and a short-circuit current wave. The open-circuit voltage waveform is defined as a 1.2/50 µs impulse, where 1.2 µs represents the virtual front time (the time for the voltage to rise from 10% to 90% of its peak) and 50 µs is the virtual time to half-value on the tail. Concurrently, the short-circuit current waveform is defined as an 8/20 µs impulse (8 µs front time, 20 µs time to half-value).

This combination is crucial. When the generator is connected to an EUT with a non-infinite impedance, the actual voltage and current delivered will differ from the open-circuit and short-circuit values. The generator’s output is designed so that the resulting voltage and current waveforms across the EUT’s terminals maintain a shape that is a realistic representation of a surge event occurring within a typical power distribution network. The coupling/decoupling network (CDN), an integral part of the test system, serves to apply the surge common-mode (between line and ground) or differential-mode (between lines) while preventing the surge energy from propagating back into the main power supply and protecting the auxiliary equipment.

The LISUN SG61000-5 Surge Generator: Architectural Overview

The LISUN SG61000-5 Surge Generator embodies a state-of-the-art implementation of the combined wave generation principle. It is engineered to meet and exceed the requirements of major international and industry-specific standards, including IEC 61000-4-5, IEC 61000-6-2, IEC 61000-6-4, and ISO 7637-2. Its architecture is predicated on achieving high precision, operational safety, and user configurability for a diverse range of testing scenarios.

At its core, the SG61000-5 utilizes a programmable high-voltage DC power supply to charge a primary energy storage capacitor. This stored energy is then discharged via a high-voltage switch, such as a thyratron or a solid-state switch, into a wave-shaping network. This network, comprising a series of precision resistors, inductors, and additional capacitors, is meticulously calibrated to mold the discharge pulse into the standardized 1.2/50 µs voltage and 8/20 µs current waveforms. The system incorporates a sophisticated trigger and control unit, allowing for both manual initiation and automated, software-driven test sequences via a PC interface. A key feature is the integrated coupling/decoupling network, which can be configured for various test setups, including line-to-line, line-to-ground, and telecommunications line testing.

Table 1: Key Specifications of the LISUN SG61000-5 Surge Generator
| Parameter | Specification | Notes |
| :— | :— | :— |
| Output Voltage | 0.2 – 6.2 kV (Single Phase) / 0.2 – 12.4 kV (Three Phase) | Continuously adjustable |
| Output Current | 0.1 – 3.1 kA (8/20 µs) | Capable of delivering high surge currents |
| Waveform Compliance | 1.2/50 µs (Open Circuit Voltage), 8/20 µs (Short Circuit Current) | Meets IEC 61000-4-5 tolerance limits |
| Phase Angle Control | 0° – 360°, ±10° resolution | Synchronizes surge injection with AC power phase |
| Polarity | Positive, Negative | Switchable for comprehensive testing |
| Coupling Modes | Common Mode, Differential Mode | Via internal or external CDNs |
| Communication Interface | RS232 / GPIB / Ethernet (LAN) | Enables remote control and automation |

Industry-Specific Application Scenarios

The application of combined wave testing spans a vast spectrum of industries, each with unique vulnerabilities and compliance requirements.

Lighting Fixtures and Industrial Equipment: Modern LED drivers and industrial motor drives incorporate sensitive switching power supplies and control circuitry. The SG6100-5 is used to verify that surge protection devices (SPDs) and filtering within these systems can clamp transient overvoltages, preventing catastrophic failure of power semiconductors and ensuring continuous operation in electrically noisy industrial environments.

Household Appliances and Power Tools: As appliances become more intelligent, their PCBs are increasingly susceptible. Testing with the SG61000-5 ensures that a voltage surge from, for example, a compressor cycling in a refrigerator or the universal motor in a power tool, does not cause malfunction or safety hazards.

Medical Devices and Automotive Electronics: Patient-connected medical equipment requires an exceptionally high degree of reliability. Surge testing validates isolation barriers and protection circuits to prevent any risk to the patient. In the automobile industry, the SG61000-5, configured for ISO 7637-2 pulses, simulates transients from load-dump events or inductive load switching, ensuring the robustness of engine control units (ECUs), infotainment systems, and advanced driver-assistance systems (ADAS).

Communication Transmission and Information Technology Equipment: Data centers and network infrastructure must maintain uptime. Surge immunity testing on communication ports (e.g., Ethernet, DSL) using specialized CDNs ensures that data integrity is preserved and hardware is protected from surges induced on long cable runs or from lightning strikes on external lines.

Aerospace, Rail Transit, and Power Equipment: In spacecraft and rail transit systems, electrical noise is pervasive. Testing for rail transit applications often involves more severe test levels as defined by standards like EN 50155. For power equipment such as inverters and protective relays, surge immunity is non-negotiable for grid stability and safety. The high-output capability of the SG61000-5 makes it suitable for testing these robust but critical systems.

Advanced Testing Methodologies and Synchronization

Beyond basic surge application, advanced methodologies are essential for uncovering subtle failure modes. Phase-angle synchronization is a critical feature of generators like the SG61000-5. By precisely controlling the point on the AC power sine wave at which the surge is injected, testers can identify vulnerabilities that only occur at voltage zero-crossings or peaks, where semiconductor stress may be maximized. Repetitive surge testing, another advanced capability, subjects the EUT to a sequence of surges at a defined repetition rate. This stresses thermal management systems and can reveal cumulative degradation in protective components like metal-oxide varistors (MOVs) that a single surge might not.

Furthermore, testing must account for multiple application points and coupling paths. A comprehensive test plan will involve applying surges in common mode (all lines to ground) and differential mode (line-to-line), as the propagation paths and the effectiveness of the EUT’s defenses can differ significantly between these modes. The use of current and voltage probes, along with the generator’s internal monitoring, allows for precise verification that the correct waveform is being delivered to the EUT, a practice mandated by quality assurance protocols.

Competitive Advantages of the SG61000-5 System

The LISUN SG61000-5 differentiates itself through a combination of precision, versatility, and user-centric design. Its waveform accuracy is maintained even at low voltage levels, a challenge for some generators, ensuring compliance across the entire test range. The integration of a high-precision phase angle controller provides a distinct advantage for testing power supplies and other phase-sensitive equipment, allowing for the discovery of hard-to-find faults.

The system’s modular architecture, supporting external CDNs for non-standard or high-current applications, provides exceptional flexibility for R&D and certification labs that handle a wide variety of products, from low-voltage electrical appliances to power equipment. The comprehensive software suite enables the creation, execution, and documentation of complex test sequences, improving lab efficiency and ensuring traceability for audit purposes. Finally, its compliance with a broad set of international and industry-specific standards makes it a single-solution instrument for manufacturers operating in global markets, reducing the need for multiple, specialized test systems.

Frequently Asked Questions

What is the significance of the 1.2/50 µs and 8/20 µs waveform definitions?
These time parameters are the internationally agreed-upon metrics that define the shape of a standardized surge pulse. The 1.2/50 µs voltage wave simulates the voltage stress imposed on insulation, while the 8/20 µs current wave simulates the follow-on current that protective components like varistors or gas discharge tubes must safely divert. Their combination ensures the test is representative of both the initial voltage spike and the subsequent energy discharge of a real-world surge event.

How does the coupling/decoupling network (CDN) function during a test?
The CDN serves two primary functions. First, it couples the surge pulse from the generator onto the power or signal lines supplying the EUT. Second, and equally important, it decouples the surge energy, preventing it from flowing back into the public power network and affecting other laboratory equipment or the AC source itself. It provides a defined impedance path for the surge while presenting a high impedance at surge frequencies to the auxiliary circuits.

Can the SG61000-5 be used for testing telecommunications and data lines?
Yes, but this requires the use of specialized external coupling networks. While the main generator unit produces the standard combined wave, the application of this surge to balanced lines like Ethernet, RS485, or telephone lines necessitates a CDN designed for the specific impedance and signal type of those lines. The SG61000-5 is designed to interface with these external CDNs to provide a complete testing solution for communication ports.

Why is phase angle control a critical feature for surge immunity testing?
The stress imposed on an EUT’s power supply circuitry can vary dramatically depending on the instantaneous AC input voltage at the moment of the surge. Injecting a surge at the AC peak voltage may test the clamping capability of protective components, while injection at a zero-crossing may test the resilience of the control logic and soft-start circuits. Phase angle control allows test engineers to perform a more thorough and revealing assessment of the EUT’s surge immunity across all operational conditions.