## What the INGVAR Is The **INGVAR** is a **primary current injection test system** designed to generate high, controlled currents for testing electrical equipment under realistic conditions. Instead of simulating signals at low levels, INGVAR pushes actual current through the device under test. This makes it possible to see how circuit breakers, relays, reclosers, and other components behave during fault-like conditions. By testing with real current, engineers and technicians can verify that protective systems will respond correctly when needed. ## When You Would Use It You would use an INGVAR any time you need to confirm the **true performance** of a protective device. For example, it is essential for: - Checking the **pickup and trip times** of protective relays. - Verifying that **circuit breakers** operate correctly at both long-time and instantaneous trip levels. - Testing **reclosers** and **sectionalizers** under simulated fault current conditions. - Assessing **current transformers** for ratio and saturation behavior. This makes the INGVAR valuable in utility substations, industrial plants, and commissioning projects where system reliability is critical. ## The Importance of Test Cables One of the most critical factors in getting the best performance from INGVAR is the quality of the test leads. The system can only deliver as much current as the total circuit impedance will allow, and a surprising amount of that impedance often comes from the cables themselves. To minimize losses, several best practices should always be followed: - **Keep cables as short as possible.** Every extra meter adds unwanted resistance and inductance, reducing the current that can be delivered. - **Use thick conductors or multiple cables in parallel.** Larger cross-sectional area reduces resistance and helps carry high currents safely. - **Twist positive and negative cables together.** This cancels out magnetic fields and lowers inductive reactance, allowing higher current flow with less voltage drop. - **Clean and tighten connections.** Brushing contact surfaces and ensuring clamps are secure reduces contact resistance, which otherwise becomes a bottleneck. Even though these details may seem small, they can mean the difference between only reaching a few amps versus successfully driving several thousand amps into a breaker or relay. ## Safety First: Isolation and Lockout/Tagout Before setting up INGVAR, it is critical to **fully isolate the equipment under test**. All circuits must be confirmed de-energized using appropriate test instruments. Once isolation is verified, apply your facility’s **Lockout/Tagout (LOTO)** procedures to secure all energy sources. This prevents accidental energization during testing and ensures a safe work zone for all personnel. No connections should be made to INGVAR until LOTO is in place and verified. ## Setting Up the INGVAR Before any connections are made, safety is the first priority. The unit’s power should be off, as output terminals may remain energized after a test. The Current Unit must be connected directly to the device under test with clean, secure clamps. To reduce losses, the leads should be short, thick, and twisted together; in some cases, multiple leads in parallel are used. The INGVAR can be connected in two configurations: - **Series** when higher voltage is needed to push current through high-impedance loads. - **Parallel** when maximum current is required at low impedance. Grounding is also critical. Both the Control Unit and the Current Unit must be tied to the same protective ground as the facility to ensure safe operation. ## Operating the Test System Once installed, the system is operated through its control panel. Different application modes can be selected, such as **normal injection**, **pulsed output**, **recloser testing**, or **sectionalizer testing**. During current adjustment, the **I/30 function** can be used. This reduces the output to one-thirtieth of the set value, allowing precise adjustment close to the expected trip level without accidentally triggering the device. When ready, the operator disables I/30 and applies full current using either a timed injection or a momentary burst. The system’s display provides real-time values of current and, when relevant, operating time. Results can be held on screen or exported to a PC for record-keeping. ## What You Can Test The INGVAR’s flexibility makes it useful for a wide range of equipment, including: - **Circuit breakers** – measuring pickup and trip times. - **Protective relays** – verifying operating curves and settings. - **Reclosers and sectionalizers** – simulating fault sequences. - **Current transformers** – evaluating saturation and ratio performance. Because it delivers thousands of amps at low voltage, the INGVAR can test both small and large devices with precision. ## Final Thoughts The INGVAR is more than just a current source; it is a comprehensive tool for ensuring electrical protection systems work as designed. By combining powerful current injection with versatile control and safety features, it allows technicians to perform realistic, reliable tests. Whether in a maintenance program, a commissioning project, or a troubleshooting situation, the INGVAR gives confidence that protective devices will respond properly when a fault occurs. [Megger INGVAR](https://www.megger.com/en-us/products/ingvar-primary-current-injection-test-system) [Megger INGVAR User Guide](https://www.megger.com/sites/g/files/utfabz201/files/acquiadam_assets/2018-10/INGVAR_UG_en.pdf?changed=1669710315)