EGIL200 circuit breaker analyser

There are many reasons for testing circuit breakers. Some of the most important are to ensure they:

• Protect expensive equipment
• Prevent outages that lead to loss of income
• Provide reliability of the electricity supply
• Prevent downtime and darkness
• Perform as expected

Some circuit breakers are equipped with pre-insertion resistors (PIR) for closing operations, typically on higher voltage transmission CBs or capacitor bank applications. The PIR closes first (typically 5 to 10 ms), and then the interrupter closes afterward. The PIR protects the breaker contacts from overvoltages and inrush currents. Therefore, accurate timing and measured values of the PIRs are crucial to ensure the circuit breaker is operating correctly, preventing circuit breaker failure and damage to the contacts. For a more detailed explanation of PIRs, refer to the Megger circuit breaker application guide.

The EGIL200 has on-board memory and software that allows you to store your results directly onto the unit. Each circuit breaker is saved as a unique asset, and a record of each test will be saved under the circuit breaker. The individual breakers can be exported to software on a PC for data storage as well.

No, the EGIL is a standalone unit operated by the built-in 7-inch touch screen. You can export results to a PC for storage and analysis, but all testing is performed directly onboard the EGIL.

The TM units and the previous EGIL use CABA Win and .arc files to control the units and analyse and database results. The EGIL200 has switched to a .zip file. You can convert older .arc files through CABA Win, and you can import this file onto the EGIL, where you can view previous results and add a new test to the same file. You can also view EGIL200 files in CABA Win, but you cannot use the software to control the unit. 

The EGIL was designed with safety and simplicity at the forefront. The on-screen, breaker focussed test setup is simple and intuitive to use. The on-screen connection diagram highlights all channels in use, so you don’t miss a connection. 

The EGIL is a lightweight, portable circuit breaker analyser, so a power supply is not incorporated to save weight, given the majority of times when you want to test with station voltage. When a variable voltage supply is needed, Megger has a B10E accessory that can power the circuit breaker.

The EGIL can be configured to test up to four breaks per phase and three motion channels simultaneously. If the EGIL doesn’t have enough channels to test everything at once on the circuit breaker, or you have custom test plans you want to create or work with, Megger recommends our TM line of circuit breaker analysers that can provide more advanced testing. You should note that the EGIL allows testing phase by phase, so this option can be used if there are insufficient channels on the EGIL200.

The EGIL is a time and travel analyser used to test medium voltage (MV) to extra-high voltage (EHV) AC circuit breakers (CBs). There are many different types and designs of AC CBs. However, from a testing perspective, there are two main types: 

• Low voltage (LV) circuit breakers that have intelligence built in to trip automatically when the current exceeds a specific value for a certain amount of time. 
• High voltage (HV) circuit breakers that depend on relays powered by station voltage to tell the CB when to operate.

 LV circuit breakers, rated up to 1000 V, are tested by injecting current through the contacts and measuring the time it takes to interrupt the current. These circuit breaker types are tested with a primary current injection unit such as the Megger SPI, Oden, and DDA. The EGIL is a circuit breaker time and travel analyser designed to test distribution and transmission CBs. The EGIL sends a control pulse to the CB and measures the time it takes for the contacts to separate or make contact, depending on the operation. The EGIL can be configured with different channels. Therefore, the types of circuit breakers it can test depend on the number of channels in the EGIL and the number of breaks the circuit breaker has. The EGIL200 is designed to test in high noise environments and can test circuit breakers up to 765 kV

There are multiple configurations of the EGIL available, and your ideal configuration depends on the type of CBs you have and the measurements you want to perform. If you only have MV CBs to test, i.e., rack in, rack out, and vacuum type, then the EGIL211 is all you need. This configuration can test one break per phase of all three phases simultaneously and has one analogue input for measuring the travel or motion of the interrupter. As you move up in voltage levels and into transmission-type CBs, the breaker may have multiple breaks per phase and multiple operating mechanisms. The correct EGIL will need to be selected based on the maximum number of breaks per phase and the number of mechanisms your CBs have. The EGIL200 can be configured to measure up to four breaks per phase and three operating mechanisms simultaneously. If you are planning on testing transmission breakers, an option with three analogue channels and a high voltage lead kit is necessary. We also recommend opting for a minimum of two breaks per phase to ensure flexibility. The EGIL software allows for testing a CB phase by phase in case you do not have enough channels to test all contacts simultaneously. 

The hardware of the EGIL is set once it is built, so it cannot be upgraded. You can add some optional features later with software or hardware accessories. The software can be upgraded to use these additional features and accessories if the EGIL has enough channels.

With a multitude of different circuit breaker (CB) designs and manufacturers, there are many different tests that you can perform. Some tests are common to all CBs, and some design specific. Megger has an extensive set of accessories available for comprehensive testing of your circuit breaker. You can order the EGIL with different lead sets based on the breakers you will encounter. These will cover the operation of the CB, timing contacts (Main, PIR, Aux), and operational parameters of coil current and station voltage. We also recommend motion transducers and, occasionally, breaker-specific accessories based on the CB you are testing. See the accessories data sheet above for further details. 

Travel is an important aspect of a circuit breaker’s operation. With a travel curve, the overall mechanism and interrupter function is evaluated. Critical parameters such as stroke, overtravel, and rebound are recorded, and you can correct faulty operation before excessive wear or damage to the circuit breaker occurs. If you are only measuring timing, note that the circuit breaker times can be within specification whilst the velocity of the interrupter is not sufficient to extinguish the arc. For a complete evaluation of the CB, we always recommend travel measurements.

There are two main types of transducers: rotary and linear. Rotary transducers are small and generally easy to mount onto the circuit breaker. However, a conversion table or conversion constant is required to translate rotary motion into linear motion. A linear transducer may be harder to mount to the circuit breaker, but it often provides a one-to-one translation of motion, so no conversion is required. The type of transducer needed depends on the manufacturer, breaker, and mechanism. Typically, a rotary transducer is required for live tank breakers. A linear transducer is most often required for vacuum, dead tank SF6, and bulk oil circuit breakers. It is best to consult the circuit breaker manual or manufacturer, but a general rule of thumb is a small linear transducer, 50 mm or less, for vacuum circuit breakers, a digital rotary transducer for live tank SF6 breakers (and some SF6 dead tank), a 200 to 300 mm linear transducer for SF6 dead tank circuit breakers, and a 500 to 600 mm linear transducer for bulk oil circuit breakers. Megger has multiple linear and rotary transducer mounting kits that you can use on various circuit breakers as well as manufacturer and mechanism-specific circuit breakers to meet all your transducer needs. Check the circuit breaker accessories guide for a list of transducers available. 

Megger has various leads, accessories, and transducer mounting kits to help make your circuit breaker testing easier. Check out the circuit breaker accessories guide for a complete list of circuit breaker accessories.

NETA recommendations for motion tests depend on the type of circuit breaker. According to NETA ATS and MTS, time and travel analysis is recommended but not required for medium vacuum circuit breakers. For oil circuit breakers and SF6 circuit breakers, NETA requires a time and travel analysis.

Basic testing for all breakers is the same. You want to record coil current, station voltage, contact resistance, contact times, and travel and, from there, calculate specific parameters. The main difference between a vacuum circuit breaker and an SF6 or OCB is that the stroke will be much shorter.

The two predominant standards are:

1. IEEE C37.09 IEEE Standard Test Procedure for AC High Voltage Circuit Breakers Rated on a Symmetrical Current Basis. 
2. IEC 62271-100 High voltage switchgear and controlgear – Part 100: Alternating current circuit breakers.

NETA also has acceptance testing (NETA ATS) and maintenance testing (NETA MTS) specifications that cover a broad range of electrical equipment, including circuit breakers.

The control pulse must energise the trip or the close coil long enough to release the corresponding latch. As long as the pulses are applied to the control circuitry with working auxiliary contacts, the AUX contacts will interrupt the current, preventing coil burnout. A typical pulse of 100 to 200 ms is sufficient to operate the coil but not long enough to burn out the coil. For a close-open operation, a short delay of 10 ms is sufficient from when the close pulse starts to when the open pulse is applied. The open pulse must be applied before the contact physically opens to test the correct close-open time. When performing an open-close (reclose) operation, you must avoid ‘pumping’ the circuit breaker. A pulse delay of 300 ms is typical to protect the circuit breaker from mechanical damage. 

First, make a reference measurement (footprint) of the circuit breaker when it is new and use this to compare future tests. Use the default settings for speed calculation points. Alternatively, if the circuit breaker is older, check to see if several breakers of the same type are available to test. Compare results with other circuit breakers of the same kind. These should be from the same manufacturer and model type, not just the same rated voltage and current. Also, you can make some checks within the test. For most breakers, all three phases should be within 1 to 2 ms of each other, but occasionally a 3 to 5 ms difference may occur for some older breakers. When the breaker has multiple breaks per phase, the difference between contacts in the same phase should be approximately 2 ms or less. On modern circuit breakers, the trip times should be between 20 to 45 ms, with close times taking longer but generally less than 60 ms. 

There are three main ways to do this:

1. Contact your circuit breaker manufacturer.
2. Find the geometric transfer function between the point of transducer attachment and the moving contact and create your own table.
3. Make a reference measurement with one transducer attached to the moving contact and one to the desired transducer attachment point. From the result of the reference measurement, you can create a table.

The circuit breaker manufacturer typically provides speed calculation points. These should be on the commissioning checklist, factory test report, or manual. If no speed calculation points are provided, then the recommended points are “Contact Touch” and 10 ms before contact touch for the close, and “Contact Separation” and 10 ms after contact separation for the open. These points provide the velocity of the contacts in the arcing zone of the interrupter. 

Megger provides multiple transducers and transducer mounting kits for both rotary and linear transducers. Some are breaker specific, while others can be used on various circuit breakers. You should connect one transducer per each mechanism. Generally, a rotary transducer is used for live tank breakers. In contrast, linear transducers are used for dead tank breakers and bulk oil circuit breakers. Vacuum circuit breakers (VCBs) have a short stroke, so often, a small linear transducer, 50 mm or less, is used for measuring the motion of VCBs. Megger has an accessories data sheet with a complete list of available transducers. If unsure about which types of circuit breakers you may encounter, the rotary mounting kit and an SF6 dead tank kit will cover most high voltage SF6 circuit breakers. The 50 mm transducer and bulk oil transducer kit will cover most VCBs and bulk oil breakers if needed. 

If available, follow the circuit breaker manufacturer’s recommendations. You can often obtain this information in the circuit breaker manual or by consulting the manufacturer. If unable to secure the manufacturer’s recommendations, the general guidance is to find a convenient place to attach the transducer. If possible, attach a linear transducer directly to the contacts or to the actuating arm of the contacts; this negates the need for a conversion table or factor. Often this is not practical, so the next best option is to connect to a point as close to the contacts as possible with minimal linkages between the connection point and the contacts. A rotary or a linear transducer may be used depending on what is the most convenient. When the transducer is not connected directly to the contacts, you will need a conversion factor or table to measure correct stroke parameters and contact velocity.Caution: ensure that neither the transducer nor its mounting components are in the path of any moving parts of the mechanism or linkages. Once you select a transducer and determine a mounting method, you should use the same transducer type and mounting location for future testing to compare results.  

The licence key for CABA Win is printed on the manual that comes with your analyser and on your CD or flash drive containing the software. It is an alphanumeric key that starts with “CABA.”

Yes. You need an external power source to operate a circuit breaker’s coils or to charge its spring motors. If station power is available, you can connect it to the Control module to operate the breaker. You will need a separate power supply if there is no station power. Megger manufactures a power supply called the B10E. 

Yes. The PIR resistance will be measured automatically by the “Timing M/R” section if the PIR value is between 10 Ω and 10 kΩ. The main and the resistor contacts are measured with the same connection. 

The EGIL200 can measure wet or dry AUX contacts. Dry contacts are contacts that do not have any voltage present on them. Wet contacts are contacts with a voltage present when they are closed. The max voltage the AUX contact can be connected to is 250 V AC and +/- 300 V DC. To turn on AUX contact measurements, select “AUX” under the measurement section on the “Test” tab. The EGIL200 will automatically sense if the contact is wet or dry.

On the “Test” tab, turn on the “Motion measurement” under the “Timing measurement”. From here, you can select “analogue” or “digital” for motion measurement type. Select the appropriate transducer settings, i.e., linear, rotary, conversion table (if needed), and speed calculation points. View the “Connections" screen for how to connect the transducer to the EGIL200. You will need one or three transducers depending on whether the circuit breaker has a common operating mechanism for all three phases or individual mechanisms for each phase.

On the “Test" tab, the “Phase” selection setting allows you to cycle between individual phases and all three phases at once.