Semiconductors Fuses

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Alvin Wilkerson
5 years ago
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1 Semiconductors Fuses

2 Three families of power semiconductors 1 Diode Thyristor Triac Bipolar transistor GTO GCT 2 MOS Power Transistor Cool MOS 3 MCT GBT EGT 2/ 25

3 History of power semiconductor Triac 1 1 Diode Thyristor Bip.Tr.Module GTO GCT 2 2 Power MOS Cool MOS Power GBT Module GBT Press Pack PM MCT EGT 3/ 25

4 Applications of power semiconductor Power GTO Transportation ndustry GBT Surge-suppressor diodes Automobiles HV cs Diodes Telecom Office equipment Home appliances 4/ 25

5 Applications of power semiconductor Network Application Converter of, V, freq. AC Cycloconverter AC Rectifier DC DC nverter AC 5/ 25 Chopper DC

6 Rectifier applications Electrolysis Galvanic plating Arc furnaces Substation Rectifiers Battery charger DC networks Generators DC Drivers V 6/ 25

7 nverter applications 50, 60 et 400 Hz Transportation 3-phase Drives - Variable speed motors On-board Networks UPS Uninterruptible Power Supplies V 7/ 25

8 Two types of faults nternal fault Diode failure Circuit breaker Load 8/ 25

9 Two types of faults External fault Circuit breaker Fault in the load 9/ 25

10 Total protection Fuses must interrupt internal and external faults FUSES SF1 FUSES SF2 L O A D L O A D Choice of the fuses location: two possibilities 2 t fuse < 2 t junction 10 / 25

11 Fuses must interrupt internal faults nternal protection The fuse must be mounted in the arms of the converter. Fuses must safety interrupt faults produced by a semiconductor failure. 2 t fuse < 2 t case 11 / 25

12 Selection criteria of a semiconductor fuse Voltage Rating V Fuse V fault Current Rating Fuse > RMS Total clearing 2 t 2 t total < 2 t semiconductor (Junction or case) nterrupting Rating R Fuse > fault Arc Voltage V fuse arc < V semiconductor 12 / 25

13 Selection of fuse voltage rating (U N ) Rectifier PWN inverter Soft starters U N V RESEAU No formula because the fuse must interrupt a capacitor discharge. A specific application leaflet with special appropriated curves must be used. U N V RESEAU Regenerative DC drive U N V RESEAU + V CONTNU 2 13 / 25

14 The fuse current rating selection requises corrective coefficients Parameters EC test conditions Working conditions inside equipments Ambient temperature Cable & bus bar dimensions Cooling Load current Frequency 30 C max. 1m long on each side of the fuse cables up to 400A 240mm² copper cable for 400A 60 mm² copper bars for 1000A (see table in annexe 1 for all ratings) Natural Continuous or stable 50 or 60 hertz 40 C to 60 C dans la plupart des cas Lenght shorter than 1m, one end can be connected to a hot component or to a water cooled heat sink. n most applications the current density in the cables or bus bars is higher. The material is cooper or aluminium. Natural or forced air cooling or water cooling Variable with overloads in most cases 0 to 20 kilohertz 14 / 25

15 Corrective coefficient for ambient temperature θ a T Cubicle Cubicle Corrective Coefficients a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect A 1 a a θ a 30 N RMS A 1 15 / 25

16 Corrective coefficient for air flow Air velocity RMS B V 1 0,05 * V V 5 m / s Corrective Coefficients a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect N A 1 RMS * B V 16 / 25

17 Corrective coefficient for connections RMS Corrective Coefficients a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect N A * B RMS * 1 V C 1 17 / 25

18 Corrective coefficient for proximity effect Corrective Coefficients L O A D d a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect For frequency > 100 Hz for most fuses C PE = 0.9 at 1000 Hz C PE = 0.8 at 5000 Hz N A 1 * B V RMS * C 1 * C PE 18 / 25

19 Corrective coefficient for duty cycle max cont EFF T t Corrective Coefficients a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect N A 1 * B V * C RMS 1 * C PE * A ' 2 19 / 25

20 Corrective coefficient for repetitive overloads Corrective Coefficients a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect F B To withstand about overloads the fuse must comply with the following condictions : F = 3 C with PSC square fuses F = 3,5 C with am fuses or ferrule UR- & gr- C ' 2 C t on Fuse prearc curve d t on C F 20 / 25

21 Corrective coefficient for non-recurrent overloads Corrective Coefficients F Cf C ' 3 Cf ' 3 0,75 a = ambient A 2 = duty cycle B 1 = air flow B 2 = thermal C 1 = connections Cf 3 = overload C PE = proximity effect F = 1,33 C To withstand about 100 à 150 overloads C t on Fuse prearc curve d t on C F 21 / 25

22 ²t characteristics 2 t(ka 2 s) 10ms (5ms) 5ms (1ms) t total (t melt ) A gr 100 RMS (ka) 22 / 25

23 DC fuse voltage rating based on system time constant (L/R) U 20ms < U 10ms L/R (ms) L/R V DC FUSE 20 mportant! FAULT > MN FAULT LEVEL (defined by charts) 10 U A U B V DC FUSE 23 / 25

24 Example of a large plant (cement, steel mill ) 24 / 25

25 25 / 25

Power Electronics. Contents

Power Electronics. Contents Power Electronics Overview Contents Electronic Devices Power, Electric, Magnetic circuits Rectifiers (1-ph, 3-ph) Converters, controlled rectifiers Inverters (1-ph, 3-ph) Power system harmonics Choppers