A

LSTO

M 2

014.

All

right

s re

serv

ed.

XX49

50BF

Fault records Disturbance Record

Measurements

PSL

Local Communication

2nd Remote comm. port

Remote comm. port

Current Differential Relay P54x

LEDs

conventional signalling available in all models

optional / model specific

protectioncommunication

I

V

Self monitoring

85

87 50/51 50N/51N

BC

Neutral currentfrom parallel line(if present)

IM

IE sen

1 Opticport

2ndst Opticport

79

Ia Ib

Ic

IS1

IS2

Differentialcurrent| Idiff |

Bias current| Ibias |

Trip

Restrain

Percentagebias k2

Percentagebias k1

| Idiff | = | Ia + Ib +Ic || Ibias | = 0.5 ( |Ia| + | Ib| + | Ic |)The relay operates when

(1) For Ibias < IS2Idiff > k1 Ibias + IS1

(2) For Ibias > IS2Idiff > k2 Ibias (k2 k1) IS2 + IS1

P540

P590Optical fibers

PCMMUX

Electricalconnections

Multiplexedlink

Other protection andtelecommunication

equipment

P542 P541

P540 P540

Optical fibers

P540 P540

P540

P543

P590 Electricalinterface

P543

P590

Single or dual fiber optic communications

Multiplexedlink

850nm1300nm1550nm

87 Current differential

67/50/51 Directional overcurrent and earth fault

21 Two or three zone distance21Single zone

distanceA B

P540 Optical fibers

Multiplexedlink

Other protection and telecommunication

equipment

PCMMUX

Compliant IEE C37.94 TM

IEEE-MI

IEEE-VI

US CO2

US COBIEEE-EI

10 0

1 0

1

0.1100101

Current (Multiples of Is)

Ope

ratin

gtim

e (s)

UK LTI

IEC SI

IEC VI

IEC EI

1000

10 0

1 0

1

0.1100101

Curren t (Multiples of Is)

Ope

ratin

gtim

e (s)

A

LSTO

M 2

014.

All

right

s re

serv

ed.