07 SEP-602A_Fuse Failure

Substation Automation and Protection Training

REL 670 Line Distance Protection IED

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ABB AB, 2007

Fuse failure

2007-10-03

Substation Automation and Protection Training

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ABB AB, 2007

FUSE FAILURE – the problem

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Substation Automation and Protection Training

FUSE FAILURE – the idea Fuse failure function detects the loss of signal from VTs. This information is used to block distance protection function and any other voltage related function.

To Block Voltage related functions

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ABB AB, 2007

ZM01 ZM02 ZM03 ZM04 ZM05 2007-10-03

Substation Automation and Protection Training

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FSD – the algorithms Solidly earthed systems Zero sequence algorithm. Detection of Fuse Failure: high value of zero sequence voltage (3Uo>) absence of zero sequence current (3Io) absence of negative sequence current (3I2 and I> check: The line had normal operating conditions for at least 200 ms before the fuse failure was activated

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ABB AB, 2007

Dead phase detection prevents activation of fuse failure during single pole A/R (when temporary unbalance in the primary system could cause unwanted activation of fuse failure signal)

2007-10-03

Substation Automation and Protection Training

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FSD – the algorithms MCB trips generally three phase (3-phase fuse failure) All the three voltages are missing at the same time It is impossible to detect a negative sequence voltage or a zero sequence voltage.

Detection of Fuse (MCB) Failure:

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ABB AB, 2007

Auxiliary contact from the MCB connected to a binary input of the terminal

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Substation Automation and Protection Training

FSD – Presence of line Disconnector PRESENCE OF LINE DISCONNECTOR

If the line disconnector is open, the undervoltage function could trip.

U<

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ABB AB, 2007

An auxiliary contact from the disconnector feeds the information CB opened to FUSE FAILURE which operates the signal FSD1-BLKU.

V

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Substation Automation and Protection Training

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FSD – Busbar switching (or 3-phase fuse failure) During busbar switching it can happen that for a while none of the 2 VTs is connected to the terminal.

All the three voltages are missing at the same time It is impossible to detect a negative sequence voltage or a zero sequence voltage. MCB does not trip because there is no failure in secondary circuit.

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ABB AB, 2007

No fuse failure is detected and impedance protection might trip! 2007-10-03 8

Substation Automation and Protection Training

0 Zm = = 0 I

FSD – Busbar switching (or 3-phase fuse failure) In this situation FUSE should also operate:

ΔU/Δt

Delta U and Delta I algorithm: The delta current and delta voltage algorithm, detects a fuse failure if a sufficient negative change in voltage amplitude without a sufficient change in current amplitude is detected.

ΔI/Δt

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ABB AB, 2007

This algorithm only operates if the circuit breaker is closed.

2007-10-03

Substation Automation and Protection Training

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FSD – (RFUF) – Settings

What happens in case of “real fuse failure”? 3Io or 3I2 is more or less very small, so which algorithm will be choosen?

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ABB AB, 2007

Actually it does not matter which one will be chosen because they both work well in case of “real fuse failure”. This algorithm has been done to increase the security during network unbalances (single phase opening, faults etc.). 2007-10-03 10

Substation Automation and Protection Training

FSD – Settings

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ABB AB, 2007

Settings for “>>“ and “