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POWER FACTOR CORRECTION SWITCHBOARD FAILURES

Russell Lee FIEAust CPEng

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Introduction

Power Factor

Correction is a tool

which can save your

client money, but to

do so, it must be

prudently applied.

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CAPACITORS WILL FAIL

With the introduction and now wide-

spread use of metallised

polypropylene capacitors in

particular, the incidence of fires

because of capacitor failure and

ignition must be taken into account

during design, operation and

maintenance of switchboards.

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NOT IF. WHEN

The incidence of fires does not

appear to me to be greater than

that for large main or distribution

switchboards, but it is the

physical relationship between

PFC equipment and associated

switchboards which is the issue.

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FAILURE MODE 1

Short circuit in

capacitance

media overheats

the material which

bursts from the

plastic casing and

ignites.

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FAILURE MODE 2

Short Circuit.

Overpressure.

The casing

bursts.

Pressure relief

often does not

respond

quickly enough

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UNDERLYING FACTORS

•High Operating Temperature.

•Sensitivity to Moisture.

•Failure to Self-heal

•Sensitivity to Harmonics.

•Poor Quality Film.

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EXAMPLE 1.1 – Burst Capacitor

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EXAMPLE 1.2 – Impact Dent

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EXAMPLE 2.1 – Main Swbd. Overheating of Capacitor.

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EXAMPLE 3.1 –Fail to Self-Heal

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EXAMPLE 3.2 – Material ejected and ignited

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EXAMPLE 3.3 - Ignition

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EXAMPLE 4.1 - Catastrophe

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EXAMPLE 4.2 – Don’t know why

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PFC 101.1

NEVER PUT ALL YOUR EGGS IN

ONE BASKET.

THINK.

ASK THE QUESTION… WHAT

IF????

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PFC 101.2

FORGET ECONOMICS AND

SAVING SPACE.

THINK SAFETY AND

RELIABILITY.

AVOID A RISK IF AT ALL

POSSIBLE.

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PFC 101.3

IT IS UNLIKELY TO HAPPEN

BUT THINK OF THE IMPACT IF

THE PFC EQUIPMENT CATCHES

FIRE.

IT IS LIKELY TO BE THE SAME

AS IF THE SWITCHBOARD

FAILED.

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PFC 101.4

NEVER PUT THE PFC EQUIPMENT

IN THE SAME ROOM AS THE MAIN

SWITCHBOARD OR MOTOR

CONTROL CENTRE, OR OTHER

APPARATUS FOR THAT MATTER.

PUT THE PFC GEAR IN A

SEPARATE AND FIRE ISOLATED

ROOM.