Circuit breaker testing – New Approach Thomas Renaudin SEEEI conference *

Circuit Breaker Testing Circuit Breakers – Design and standards Tests on Circuit Breakers CIBANO 500 © OMICRON

Definition of Circuit Breaker Basically a circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to immediately discontinue electrical flow. Ideal switch: closed open R = 0 Ω R = ∞Ω © OMICRON

Purpose of Circuit Breakers in Power Systems Network Minimize losses in closed position Open and close on command Open or close a circuit to connect the power to/from the transmission line (O - break, C - make) Open a circuit for planned maintenance (O - break) Open a circuit at system fault to protect the system behind the circuit breaker (O break, O-C reclose, O-CO, auto-reclose) Isolate between poles, open contacts and earth x Circuit Breaker Busbar Disconnector x Circuit Breaker Power Transformer © OMICRON

Circuit Breaker Components Source: ABB, [RUS07] © OMICRON

Circuit Breaker Components A: interrupter chamber B: insulated support column C: support structure D: central cubical E: wiring F: operating mechanism Source: Siemens © OMICRON

Standards – ANSI C37.04-1999 Standard ratings defined C37.06-2000 Schedule of preferred ratings C37.09-1999 Type tests Routine tests C37.081, C37.082, IEEE 693 © OMICRON

Standards – IEC IEC 62271-100, 2001 Type, routine & field tests Timing definitions Guide for selection and specification IEC 60694, 2001 Normal service conditions Schedule of preferred ratings Altitude correction IEC 60427, IEC 60815, IEC 60529, IEC 61166, IEC 61233 © OMICRON

IEC - timing definition © OMICRON

Circuit Breaker Testing Circuit Breakers – Design and standards Tests on Circuit Breakers CIBANO 500 © OMICRON

What is usually needed to test breakers Timing Analyzer µΩ - Meter CB Supply Rewiring for each test Individual µΩ-Measurement for each interrupter Collect data for test report © OMICRON

Typical tests on circuit breakers Minimum pick-up test Static resistance or contact resistance test (µOhm) Timing of main and auxiliary contacts different operations (O, C, OC, CO, OCO, COCO, OCOCO,...) undervoltage test coil currents Motor current Contact travel (motion) of main contacts Dynamic contact resistance (DRM) © OMICRON

1. Minimum Pick-up Test © OMICRON

Indicates the lowest voltage to operate the trip or close coil 1. Minimum Pick-up Test Indicates the lowest voltage to operate the trip or close coil Start at a certain voltage level Try to operate If not working increase voltage and try again Ramp the voltage pulse until minimum voltage is reached with which the circuit breaker switches Everybody has a „selfmade“ solution for this test © OMICRON

2. Contact Resistance Test Conventional Setup © OMICRON

2. Contact Resistance Test Test is performed with a µOhm-Meter A lot of different test devices on the market (weight, handling, output current and accuracy) Inject a high current Measurement of a small voltage in a noisy environment Use 4-wire technique to connect © OMICRON

Connect to all main contacts Connect to trip & close coil 3a. Timing Test Connect to all main contacts Connect to trip & close coil Voltage supply required Conventional Setup Time-consuming and error-prone © OMICRON

3a. Timing Test - Measured Values Open Time, Close Time, Contact Spread, Phase Spread, Trip-Free Time, Reclose Time © OMICRON

3b. Timing undervoltage condition Coils are normally driven by station battery What happens if battery condition is not the best Perform a test with reduced supply voltage (e.g. 80 %) Check times for under voltage does it work anyhow are there any delays compared to nominal voltage? Measure the overall times and compare to manufacturer values © OMICRON

Important tool in circuit breaker analysis 3c. Coil Current Important tool in circuit breaker analysis Detect potential problems in actuating coils Reveal information on power supply Comparison is best method of analysis © OMICRON

Connect source to charging motor or use current clamp 4. Motor Current Connect source to charging motor or use current clamp Check charging times and charging currents Compare with previous measurements © OMICRON

Functional Breaker Model 5. Contact Travel Functional Breaker Model © OMICRON Page 22

5. Contact Travel - Travel Measurement to find out: Mechanical defects of the cinematic chain Overall mechanical performance Slow operation due to jammed mechanism Deterioration of mechanical damping Contact wear Arcing contact length (in combination with DRM) © OMICRON

6. Dynamic Resistance Measurement (DRM) Recording the contact resistance during breaker operation (resistance over time) Combination of contact resistance, timing and travel measurements Inject high current Start recording A & V Operate Circuit Breaker Calculate Resistance © OMICRON

6. Dynamic Resistance Measurement (DRM) Use DRM to find out Problems with contact fingers Lubrication problems The arcing contact length © OMICRON Page 25

6. DRM Diagnosis: arcing contact length main contact motion arcing contact length dynamic resistance coil current ms © OMICRON Page 26

Circuit Breaker Testing Circuit Breakers – Design and standards Tests on Circuit Breakers CIBANO 500 © OMICRON

Conventional Setup for Circuit Breaker Testing Rewiring between micro- ohm measurement and timing tests Lots of cables Time-consuming and error-prone Long test cables create inductive loops which catch interferences External supply or station battery required Mirco-ohm measurement Timing Tests © OMICRON

CIBANO 500 – 3-in-1 Test System Timing analyzer Possible operations: O, C, CO, OC, O-CO, CO-CO, O-CO-CO Motion measurement is possible in parrallel Micro-ohm meter Static AND dynamic contact resistance test Powerful coil and motor stabilized supply Coil/motor current analysis Undervoltage condition test Minimum pick-up test Tests are possible without station battery © OMICRON

CIBANO 500 – one system for all types of breakers Medium-voltage circuit breakers High-voltage circuit breakers (Live Tank) High-voltage circuit breakers (Dead Tank) © OMICRON

Unique connection concept CB MC2 CIBANO 500 CB TN3 © OMICRON

Modular concept for simplified testing – Main Contact Module CB MC2 2 high-current outputs and 2 sensitive voltage measurement channels Keeps high-current cables as short as possible minimizing the weight of the necessary cables A digitized measuring signal is produced directly at the interrupter keeping analog cables as short as possible very low noise interference Only one connection cable to the main unit fast set-up and reduced risk of wiring errors Both sides grounded test possible © OMICRON

Unique connection concept © OMICRON

Unique connection concept © OMICRON

Modular concept for simplified testing – Transducer Node CB TN3 Accessory for motion/contact travel test 3 analog and digital channels for data acquisition of linear or rotational motion sensors Interference-free digital transmission of results via one cable © OMICRON

Powerful software support Primary Test Manager software supports all tests One combined test report for all tests © OMICRON

Benefits of all-in-one OMICRON approach 3-in-1 system combines: timing analyzer micro-ohmmeter powerful AC/DC supply One wiring for all test: all-in-one / all-in-once One system for medium- and high-voltage circuit breakers Immunity to interference due to short test cables One combined report for all tests Light-weight test system for on-site testing (20 kg / 44.1 lbs) © OMICRON

© OMICRON