UNIT-2
Electyo Maqnetic PxoteCt ion
Relou S8 a awhomatie dovice wich Zeses
A
alonorma
RolayCanditiong (fautta) in electric Cirut.ad
give te to the ciscut oreaker. hen
from the fiad Cotact amd
movig codact is mwiag away frmm tn
tne fauhy pat f tue crit kosake electoic civuit is
dislonnetted .pson
fron the healty cicit.
beaty
Funttiona cana terigkicg of Relays
sengitivi y
2 selectivihy
stabiliy
4. Relialbili y
S. SPeed
b. tlomomical
Kewsitive
|.sewsitivityThe pyote ctive selay enagh
to operate at low actuating Quankities. ie voltag of tunet
velay
selectivihy- 4t is tue bosic vequisemeut off tue the
Potsible to cole t wich
which it shoud loe
yelen is foaudty amd
awd wich ig mot fouhy and shculd
isclale -te fauty Pot fomn tue one.
sole ctiviy 1k acieved in two ways, tno e
resPondg
i) Unit sgten prote tion ony individual wit
) Non- wit Sytem Protetion All uits mnay ropord tu a
iven faut
3 staloility loe kog to
eay ne
witwtand loge cuonunts flow twwugdh tue poteetive
Zone duing the enlenal fautts
, Relialiliy The velay ahoudd be velable i4 a sic
wueu if i Yeguired (wheu
faut enits). The dosired etialailiky of prote (tive Bsten
i8 q5%
S. Spe edi A pYotetive to
digcannelt tne 8ection inod to mimi mise the
t
dawge of the eguipnet. he cperatiwy time of the elays
will be less tau
6. EConemital :- cEenomic oSPect plas inpottaut ole in Hhe
choice cf pantida protective systen, s pen tue gales
velay cofl khadd
-tue yelay less thau s % of total csl
Basic Definitions
Pick up leveli- 44t i6is minimun alue ¢ acttating
tue
quautity voneut o vaitge) albove wick t e selay operates.
Reset lovel t is te maximuun Value f attatig quanti
uwhich a velay cpes its coutacts
Ccustheut valtrge) lbelow
Lomes to orqinal position.
Theghcld wlue
10A
Rday cantats clsin
Rolay contact; chn
Reset level Pickup lavel
Reset tine oPenatig tine
oPeatia time' 3t is tue tine elapse beteen tue inta
loeComes fate Hhau the et
whe -tue actuating
PicR -up Vaue to t e inatant when tthe relay Coutatts clsg
Reget time- 4t tue time elapse betweevn the iwkut
t i8is tne
when tue actuating quautiy becong tess tran the
Yeset value to tue itut when theelay catacts yehes
, to its noimal pasition.
he distace elay cpetg wheneve the impedance seen
impedane
loy tue Yelay is less tuan a prespecified vaue. Tis
distanee Knon ay tue veach af the reay.
Unden reach Tue teudency af tue Yelay to opesnate dt impRdanee
tes than a set vale i6 Hnown as wnde each.
oven Teach!- The yelay to openale at
inpe daee lagy thna set value s knoun a veseach.
principles af Relayf
thene tuo
diffeneut speratig princiles
i) electo wagneli ataction
îndu ction
i) lectro - wagmetic
D Electo- wagnetie atta ction Rdas !
qperated by virtue of suntune be ing
They velap plungen beig
athacted to t e poles af ele cto wagndt
drawn into a Solenoid.
looth de aswell o ac
’Tuee relays Ca oe operaked by
’ Types of electro agntie vela
i) Atacted amatune type Telay
) Ralaed beaw type Yelay
i) sdeoid type velay
) Attracted amate tye velay
Elecbo
M
To trip cirit
Auatue
Electyo Maqnetic PxoteCt ion
Relou S8 a awhomatie dovice wich Zeses
A
alonorma
RolayCanditiong (fautta) in electric Cirut.ad
give te to the ciscut oreaker. hen
from the fiad Cotact amd
movig codact is mwiag away frmm tn
tne fauhy pat f tue crit kosake electoic civuit is
dislonnetted .pson
fron the healty cicit.
beaty
Funttiona cana terigkicg of Relays
sengitivi y
2 selectivihy
stabiliy
4. Relialbili y
S. SPeed
b. tlomomical
Kewsitive
|.sewsitivityThe pyote ctive selay enagh
to operate at low actuating Quankities. ie voltag of tunet
velay
selectivihy- 4t is tue bosic vequisemeut off tue the
Potsible to cole t wich
which it shoud loe
yelen is foaudty amd
awd wich ig mot fouhy and shculd
isclale -te fauty Pot fomn tue one.
sole ctiviy 1k acieved in two ways, tno e
resPondg
i) Unit sgten prote tion ony individual wit
) Non- wit Sytem Protetion All uits mnay ropord tu a
iven faut
3 staloility loe kog to
eay ne
witwtand loge cuonunts flow twwugdh tue poteetive
Zone duing the enlenal fautts
, Relialiliy The velay ahoudd be velable i4 a sic
wueu if i Yeguired (wheu
faut enits). The dosired etialailiky of prote (tive Bsten
i8 q5%
S. Spe edi A pYotetive to
digcannelt tne 8ection inod to mimi mise the
t
dawge of the eguipnet. he cperatiwy time of the elays
will be less tau
6. EConemital :- cEenomic oSPect plas inpottaut ole in Hhe
choice cf pantida protective systen, s pen tue gales
velay cofl khadd
-tue yelay less thau s % of total csl
Basic Definitions
Pick up leveli- 44t i6is minimun alue ¢ acttating
tue
quautity voneut o vaitge) albove wick t e selay operates.
Reset lovel t is te maximuun Value f attatig quanti
uwhich a velay cpes its coutacts
Ccustheut valtrge) lbelow
Lomes to orqinal position.
Theghcld wlue
10A
Rday cantats clsin
Rolay contact; chn
Reset level Pickup lavel
Reset tine oPenatig tine
oPeatia time' 3t is tue tine elapse beteen tue inta
loeComes fate Hhau the et
whe -tue actuating
PicR -up Vaue to t e inatant when tthe relay Coutatts clsg
Reget time- 4t tue time elapse betweevn the iwkut
t i8is tne
when tue actuating quautiy becong tess tran the
Yeset value to tue itut when theelay catacts yehes
, to its noimal pasition.
he distace elay cpetg wheneve the impedance seen
impedane
loy tue Yelay is less tuan a prespecified vaue. Tis
distanee Knon ay tue veach af the reay.
Unden reach Tue teudency af tue Yelay to opesnate dt impRdanee
tes than a set vale i6 Hnown as wnde each.
oven Teach!- The yelay to openale at
inpe daee lagy thna set value s knoun a veseach.
principles af Relayf
thene tuo
diffeneut speratig princiles
i) electo wagneli ataction
îndu ction
i) lectro - wagmetic
D Electo- wagnetie atta ction Rdas !
qperated by virtue of suntune be ing
They velap plungen beig
athacted to t e poles af ele cto wagndt
drawn into a Solenoid.
looth de aswell o ac
’Tuee relays Ca oe operaked by
’ Types of electro agntie vela
i) Atacted amatune type Telay
) Ralaed beaw type Yelay
i) sdeoid type velay
) Attracted amate tye velay
Elecbo
M
To trip cirit
Auatue
