New industry Technology regarding to Bussmann fuse, ABB breakers, Amphenol connectors, HPS transformers, etc.

Time：2021-09-10 Author：ABPower Browse：

When the main current is at high frequency, the correction factor CPE is shown in Table 1.

The data shown in Table 1 is not accurate because it does not take into account how many fusion cores are connected in parallel, nor does it take into account the effect of distance D, but it is sufficient for fuse selection.

Frequency ( HZ ) | CPE | ||

100 | to | 500 | 0.95 |

501 | to | 1500 | 0.9 |

1501 | to | 5000 | 0.8 |

5001 | to | 10000 | 0.7 |

10001 | to | 20000 | 0.6 |

However, for most applications, only the harmonics are the high frequency components and the fast acting fuse current is: I = i0+ i1+ i2 +..+ iK

I_{0} is the main part of the current: In most cases, DC current or 50Hz current..;

I1, i2,....IK is a significant harmonic. The effective current value of the ultra fast acting fuse is:

The calculation of rated current of fuse can be equivalent to:

(That is, the total value of C_{PE} is:)

The C_{PEK} of each harmonic is a function of each harmonic frequency shown in the table above.

The rated current I_{N} of the ultra fast acting fuse can be calculated using I_{EQ} and all classic correction parameters:

(A1 is the temperature coefficient, C1 is the connection mode coefficient, and A '2 is the aging coefficient under the condition of alternating current)

Although harmonics are often uncertain, it is necessary to estimate C_{PE} based on the switching frequency of IGBT. According to Table 2, it can be estimated:

Table 2 – DC side ultra fast acting fuse | |||

Switch frequency ( HZ ) | Total C_{PE} | ||

100 | to | 500 | 1 |

501 | to | 1 500 | 0.95 |

1 501 | to | 5 000 | 0.9 |

5 001 | to | 10 000 | 0.85 |

10 001 | to | 20 000 | 0.8 |

Table 3 – A fuse is placed on the bridge arm of the inverter | |||

Switch frequency ( HZ ) | Total CPE | ||

100 | to | 500 | 1 |

501 | to | 1 500 | 0.9 |

1 501 | to | 5 000 | 0.85 |

5 001 | to | 10 000 | 0.8 |

10 001 | to | 20 000 | 0.75 |

Note: This coefficient can be applied to the estimation of the RMS of the total current, i.e. :

Thus, the fuse rating I_{N} can be calculated using I_{EQ} and all the classic correction parameters:

IGBT elements cannot operate at rated current at any frequency. In fact, IGBT elements with high voltage and current ratings are more sensitive to frequency than products with smaller ratings, and the current grade drops faster. A comparison of IGBT and fast acting fuses shows that fuses are more severely affected at low frequencies and then ultra fast acting fuses perform better at high frequencies, especially those higher than 10kHz.

Test different IGBT components with or without fuses.§7.1.., §7.2. And §7.3 show the test results using 1200 V 75 A IGBT element.

The test results of IGBT at 1200 V 75 A were as follows: the melting time at the junction was T_{1} = 35 s, and the corresponding I^{2}T was 12,700 A s

The occurrence time of the maximum peak current is t_{2} = 55 s, and the corresponding i^{2}T is 35 000 A s

The time of explosion is t_{3} = 66 s, and the corresponding i^{2}T is 48,800 A s

**7.2. Test for IGBT series 315A ultra fast acting fuses**

The test results showed that the total I^{2}T of the ultra fast acting fuse was 27,500 A S, and IGBT could not observe the external damage.

**7.3. Test of SERIES 400A fast acting fuses for IBGT**

The test results showed that the total I^{2}T of the fuse was 37000 A S, and some damage (deformation, cracking) could be seen on the shell of IGBT.

**Conclusion : All the above tests show that the ultra fast acting fuse can protect IGBT of 1200 V 75 A.The value of shell burst I ^{2}T for fuse selection can be 30 000 A S.**

Circuit parameters:

E = 600V Max

R = 10^{-3 }(including internal resistance of the selected ultra fast acting fuse).

L = 2.2 10^{-7} H

C = 2 10^{-3} F

= 10^{-4 }H

Two ultra fast acting fuses in the DC circuit (FIG. 4) : The current through the fuses is 130 AMP.

IGBT data:

Rated current at 5kHz (effective value) : 75 A

FERRAZ SHAWMUT's actual explosion I^{2}t (see §7) : 30 000 A S (but not the fuse I^{2}t at the junction = 12700 A S)

Blocking voltage: 1200V

Inverter operating conditions: IGBT operating frequency: 5 KHz-75 A effective value, environmental temperature: 50°C, natural air cooling.

Circuit characteristics of capacitance discharges without fuses:

Period T = 132 s, maximum peak current I_{max} = 53,200a, the time of the first maximum peak current t_{m} = 32 s 66 s I^{2}T of the first half wave: 93,300 A s, far greater than the I2T of the fuse at the IGBT connection.

The fuses of the PSC 690 V URD series are optional because E_{M} = 900V (see fuse data in Figures 12, 13, 14 and 15)

Remark: Ferraz Shawmut PSC 690V fuse cross reference to Bussmann PN: 170M30xx, 170M31xx, 170M32xx......

The correction factor used is:

=.894 C1 =0,85;

A3 = 0 ,80;

C_{PE} = 0, 9

The rated current I_{N} of the ultra fast acting fuse should be 238AMP.

The pre-arc time T_{P} can be calculated by the maximum d_{i}/ D_{T} when the fault occurs:

The result is multiplied by the coefficient G for the different fuse rated currents in Figure 12.

Take the fuse in 315A as an example: The graph of 0 V in Figure 13 shows the functional relationship between the pre-arc time T_{P} and G d_{i}/d_{t}.

Therefore, the ante-arc time is:

t_{p} = 14 10-6

T_{p}<T/6 can be verified, because T/6 is equal to 22, 10-6s.

When T_{P} = 14 s, the calculation result of U_{P} is:

PM = 600V, conditions U_{P} < U_{PM} can thus be validated.

The two ultra fast acting fuses will operate in series.

The arc front time is T_{P} = 14 10-6 s, and it can be confirmed that the voltage is evenly Shared between the two fuses.

Therefore, the total I^{2}t can be calculated when the fuse operates at 471/2 = 236 V.

The total I^{2}t is equal to the front I^{2}t given in the list (Figure 12) times the correction factor k (figure 14).

The curve shows that K = 1.4 when Up = 236V and I T in front of 250A fuse is 5800 A S.

The total I^{2}T of the fuse is 5800 * 1.4 = 8120 A S (much lower than the IGBT's allowable of 30,000 A2s)

I^{2}t is equal to 8120 A S

The graph shown in Figure 15 shows U_{m} = 630V.

This value is lower than the blocking voltage of IGBT.

The total arc extinguishing time of the fuse t_{t} can pass through FIG. 13

Curve estimation in.

When G D_{I} /d_{t} = 3.57 1010, t_{t }= 27 s at 380V as shown in the graph.

But the actual voltage is 236V.

Through the line

Sex interpolation method, between 0- 380V, 196V: so t_{t }= 22 10-6s

The peak permissible current I_{C} of the fast acting fuse is:

**Even under very poor working conditions, it is possible to find a suitable fast acting fuse to prevent IGBT from exploding.**

**The total I ^{2}t of the ultra fast actingfuse can be calculated from the related graph to ensure that it can provide protection.**

**The proximity effect coefficient CPE presented in this paper cannot take into account all possible cases, but they can deal with the problems encountered in the conventional design, and also enable the preliminary correct selection of the face fast fuses to be realized.**

Thanks to Xilian Fuse Institute.

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