hrc fuse knowledge
TRANSCRIPT
E l e c t r i c a l S t a n d a r d P r o d u c t s
Sw i t c h g e a r T r a i n i n g C e n t r e , C o o n o o r
HRC Fuses
WHAT IS HRC?
HRC FUSEMAIN APPLICATION AREAS
AS A SHORT CIRCUIT PROTECTIVE DEVICE IN MOTOR STARTER FEEDERS
PROTECTION OF LIGHTING & HEATING CIRCUITS
PROTECTION OF TRANSFORMERS
PROTECTION OF CABLES
WHY HRC FUSE ?• EXTREMELY HIGH BREAKING CAPACITY OF UP TO
100KA• VERY FAST OPERATION IN THE EVENT OF HEAVY
SHORT CIRCUIT (CAN INTERRUPT EVEN IN < 5 milliseconds )
• CURRENT LIMITING DEVICE‐ LIMITS SHORT CIRCUIT CURRENT TO A
VALUE LESS THAN PROSPECTIVE PEAK‐ VERY LOW LET THROUGH ENERGY
• NO MAINTENANCE REQUIRED• VERY SMALL/COMPACT SIZE• RELATIVELY LOW COST
CURRENT LIMITING FEATURE
TIME
CU
RR
EN
T
IP
IC
T1 T2
T1 = PRE-ARCING TIME
T2 = ARCING TIME
IP = PROSPECTIVE PEAK
IC = CUT-OFF CURRENT
LET‐THROUGH ENERGY(JOULE INTEGRAL)
LET-THROUGH ENERGY = i2 dt
t1
t2
= I2 t
SELECTION OF HRC FUSEPARAMETERS
RATED VOLTAGE RATED CURRENT RATED BREAKING CAPACITY BREAKING RANGE UTILIZATION CATEGORY TYPE SIZE RATED POWER DISSIPATION TIME-CURRENT CHARACTERISTICS CUT-OFF CHARACTERISTICS COORDINATION WITH STARTER DISCRIMINATION WITH OTHER SCPDs
SELECTION PARAMETERS
UTILIZATION CATEGORY ‘G’
FOR THE GENERAL APPLICATIONS
UTILIZATION CATEGORY ‘M’
FOR THE PROTECTION OF MOTOR CIRCUITS
UTILIZATION CATEGORY
SELECTION PARAMETERS
FULL RANGE BREAKING CAPACITYA CURRENT LIMITING FUSE LINK CAPABLE OFBREAKING UNDER SPECIFIED CONDITIONS ALLCURRENT WHICH CAUSE MELTING OF THE FUSEELEMENT UP TO ITS RATED BREAKINGCAPACITY
‘g’
PARTIAL RANGE BREAKING CAPACITYA CURRENT LIMITING FUSE LINKCAPABLE OF BREAKING UNDER SPECIFIEDCONDITIONS ALL CURRENT BETWEEN THELOWEST CURRENT INDICATED ON ITSOPERATING I-T CH. (K2In) AND ITS RATEDBREAKING CAPACITY
‘a’
BREAKING RANGE
SELECTION PARAMETERS
HRC FUSE LINKS
‘gG’ FUSE LINK ‘aM’ FUSE LINK
‘gG’ INDICATES FULL RANGEBREAKING CAPACITY FOR THEGENERAL APPLICATIONS
‘aM’ INDICATES PARTIALRANGE BREAKING CAPACITYFOR THE PROTECTION OF
MOTOR CKTS
TYPE
SELECTION PARAMETERS
CONVENTIONAL TIME & CURRENT FOR gG FUSE LINKS
RATED CURRENT CONVENTIONAL CONVENTIONALIn (in Amps.) TIME (in hrs.) CURRENT
Inf If
In 4 1 1.5 In 2.1 In4 < In < 16 1 1.5 In 1.9 In
16 In 63 1 1.25 In 1.6 In63 < In 160 2 1.25 In 1.6 In160 < In 400 3 1.25 In 1.6 In
400 < In 4 1.25 In 1.6 In
TYPE
SELECTION PARAMETERS
FUSES WITH FUSE LINKS HAVING
CYLINDRICALCONTACT CAPS
BLADECONTACTS
CONTACTSFOR BOLTEDCONNECTIONS
SIZE 000
SIZE 00
SIZE 0
SIZE 1
SIZE 2SIZE 3
SIZE 10 X 38
SIZE 14 X 51
SIZE 22 X 58
SIZE
SIZE 00
SIZE 0
SIZE 1SIZE 2
SIZE F
SIZE A
SIZE B
SIZE C
SELECTION PARAMETERS
AS PER IS 13703/PART 2 FOR gG FUSE LINKRATED POWER DISSIPATION
Size of Fuse
Nominal Current of Fuse (Amps.)
Maximum Permissible Power Dissipation (in Watts)
Power Dissipation of L & T make HRC Fuses (Type HN)
000 100 7.5 7.0
00 100 7.5 7.5
0 160 16.0 12.7
1 250 23.0 17.3
2 400 34.0 24.9
3 630 48.0 42.2
Cross‐Section of a HRC Fuse
Fuse ElementCeramic Body Neck Portion Low Melting Alloy
Knife Blade Type Link Nichrome Wire
Quartz Sand Fuse-Blown Indicator
SELECTION PARAMETERS
SYMMETRICAL CURRENT IN AMP
PRE-
AR
CIN
G T
IME
IN S
EC
10-2
10-1
101
104
100
103
102
3
3
3
3
3
3
FUSE RATINGS(from bottom to top)63 A80 A100 A125 A160 A200 A250 A315 A400 A500 A630 A
I-T CHARACTERISTICS
4
Pre-A
rcing Time (in S
econds)
SYMMETRICAL RMS CURRENT IN KA
CU
T-O
FF C
UR
REN
T IN
KA
(PEA
K)
SELECTION PARAMETERS
630 A500 A400 A315 A250 A200 A160 A125 A100 A80 A63 A
0.1 0.2 0.5 1 2 5 10 20 50 80
CUT-OFF CHARACTERISTICS100
50
20
10
SELECTION PARAMETERS
TYPE 1 CO - ORDINATIONREQUIRES THAT, UNDER SHORT-CIRCUIT CONDITIONS, THECONTACTOR OR STARTER SHALL CAUSE NO DANGER TOPERSONS OR INSTALATION AND MAY NOT BE SUITABLE FORFURTHER SERVICE WITHOUT REPAIR AND REPLACEMENT OFPARTS
TYPE 2 CO - ORDINATIONREQUIRES THAT, UNDER SHORT SHORT-CIRCUIT CONDITIONS,THE CONTACTOR OR STARTER SHALL CAUSE NO DANGER TOPERSONS OR INSTALLATIION AND SHALL BE SUITABLE FORFURTHER USE. THE RISK OF CONTACT WELDING ISRECOGNIZED, IN WHICH CASE THE MANUFACTURER SHALLINDICATE THE MEASURES TO BE TAKEN AS REGARDS THEMAINTENANCE OF THE EQUIPMENT
CO-ORDINATION WITH STARTER
SELECTION PARAMETERS
FOR DISCRIMINATION BETWEEN TWO FUSES,IT IS REQUIRED THAT THE UPSTREAM FUSESHOULD HAVE PRE-ARCING I2t MORE THANTHE TOTAL I2t OF THE DOWNSTREAM FUSE
COMPLIANCE WITH THE PRE-ARCING I2t AS PER IS :13703 IS DEEMED TO INSURE A DISCRIMINATIONBETWEEN FUSES WITH RATED CURRENTS IN THE RATIOOF 1.6 TO 1
DISCRIMINATION
SELECTION OF FUSE
VOLTAGE RATING OF FUSE SHOULD MATCH WITH THELINE VOLTAGE
FUSE SHOULD NOT BLOW DURING SWITCHING -ON OFLOADS WITH HIGH INRUSH CURRENTS LIKE MOTORS
BREAKING CAPACITY OF THE FUSE SHOULD BE EQUAL TO OR GREATER THAN THE FAULT LEVEL AT THAT POINT OF THE INSTALLATION
FUSE SHOULD BE ABLE TO PROVIDE PROPER DISCRMINATION WITH DOWNSTREAM SHORT CIRCUIT PROTECTIVE DEVICES
BASIC CRITERIA
SELECTION OF FUSE
WHEREVER USED WITH MOTOR STARTERS, THE FUSE SHOULD HAVE PROPER CO-ORDINATION WITH STARTER :
- THE FUSE SHOULD NOT OPERATE FOR SUCH OVERLOADS AS
MAY BE HANDLED BY OLPD
- THE FUSE DISCONNECTS THE SUPPLY TO THE MOTORSTARTER SUFFICIENTLY EARLY BEFORE THE STARTER IS DAMAGED (THE LET THROUGH ENERGY OF FUSE
SHOULD BE LOWER THAN WHAT RELAY & CONTACTOR CAN
WITHSTAND)
BASIC CRITERIA
SELECTION OF FUSE
- THE FUSE SHOULD DISCONNECT THE SUPPLY SUFFICIENTLY
EARLY SO AS THAT MOTOR STARTER IS NOT REQUIRED TO
BREAK CURRENT IN EXCESS OF ITS BREAKING CAPACITY (THE
CROSSOVER OF FUSE & RELAY CHARACTERISTICS SHOULD
TAKE PLACE BEFORE BREAKING CAPACITY OF CONTACTOR)
BASIC CRITERIA
SELECTION OF FUSET
IME
(SE
C)
CURRENT (n IrM)1 2 3 4 5 6 7 8 9 10
RELAY FUSE CONTACTORCH. CH. BR. CAPACITY
MOTORCURRENT
CROSS-OVERPOINT
TYPE 2 COORDINATION
