residual current devices in lv for the lhc j. gomez st/el-pm

RESIDUAL CURRENT RESIDUAL CURRENT DEVICES IN LV FOR THE DEVICES IN LV FOR THE LHCLHC

J. Gomez ST/EL-PMJ. Gomez ST/EL-PM

RESIDUAL CURRENT RESIDUAL CURRENT DEVICES IN LV FOR THE LHCDEVICES IN LV FOR THE LHC

Two ways of portecting againts earth Two ways of portecting againts earth faultsfaults• Over current devices.Over current devices.– Compliance with IEC 364-4Compliance with IEC 364-4

• Residual current devices.Residual current devices.– Types according IEC 60755Types according IEC 60755• A, AC, BA, AC, B


Types according IEC 60755 Over Types according IEC 60755 Over current devices.current devices.

– Type A: For sinusoidal currents or Type A: For sinusoidal currents or pulsed DC currents.pulsed DC currents.–Type AC: Detects only sinusoidal Type AC: Detects only sinusoidal

currents.currents.–Type B: For DC currents.Type B: For DC currents.


An eventual earth fault, in an electronic An eventual earth fault, in an electronic device, with a high DC component device, with a high DC component might deceive a “standard” residual might deceive a “standard” residual circuit breaker preventing it from circuit breaker preventing it from opening and consequently creating a opening and consequently creating a dangerous situation.dangerous situation.


Avoiding unwanted tripping. Avoiding unwanted tripping. • Normally due to capacitive transient Normally due to capacitive transient

leakage'sleakage's• Unknown behavior of the electronic Unknown behavior of the electronic

devices.devices.• This kind of tripping represent a lack of This kind of tripping represent a lack of

quality network and should be reduced quality network and should be reduced to a maximum.to a maximum.


Avoiding unwanted tripping. Avoiding unwanted tripping. • These currents may be generated These currents may be generated

because of the following reasons:because of the following reasons:– Long power lines. (62mA per Km)Long power lines. (62mA per Km)– Equipment containing capacitive earthed Equipment containing capacitive earthed

devices. Interference filters (ECM) placed in devices. Interference filters (ECM) placed in microcomputers generate permanent leakages microcomputers generate permanent leakages currents at 50Hz of the order of 0.5 to 1.5 mA currents at 50Hz of the order of 0.5 to 1.5 mA per device.per device.


Avoiding unwanted tripping. Avoiding unwanted tripping. • These currents may be generated These currents may be generated

because of the following reasons:because of the following reasons:– Transient leakage currents.Transient leakage currents.– High frequency leakage currents.High frequency leakage currents.– Lightning currents. Peak value 250A (8/20 Lightning currents. Peak value 250A (8/20

microseconds).microseconds).

• RCB’s against this phenomena are mark RCB’s against this phenomena are mark with a particular symbol.with a particular symbol.


ConclusionConclusion– In many cases electronic equipment are of the In many cases electronic equipment are of the

highest importance for the future safety of the highest importance for the future safety of the new accelerator. A quality non-stop supply is new accelerator. A quality non-stop supply is absolutely necessary.absolutely necessary.

– Two possibilities:Two possibilities:• No residual current devices for circuits feeding No residual current devices for circuits feeding

critical equipment. Accepted by TIS.critical equipment. Accepted by TIS.• Installation of unwanted tripping protected A Installation of unwanted tripping protected A

type residual current devicestype residual current devices. .

residual current devices in lv for the lhc j. gomez st/el-pm

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