Fusing Considerations by Brett Donjon Josh McGill

8/6/2019 Fusing Considerations by Brett Donjon Josh McGill

1/44

FUSING CONSIDERATIONS

ARE POWER FUSES DESIGNED

TO PREVENT LETHAL CURRENTS

TO PEOPLE?


2/44

HUMAN REACTIONS

to Alternating Current

(1 milli ampere (mA) = 1/1000 Amp)

1 mA Slight Tingling Sensation

110 mA Sensation of Shock

5 mA Painful Shock Begins

615 mA Let-Go Threshold Level Breached

15 mA+ Severe PainInvoluntary Movement

25 mA+ Respiratory Paralysis Begins

50 mA+ Ventricular Fibrillation Level

500 mA Lights a 60 watt light bulb


3/44


ARE POWER FUSES DESIGNEDTO PREVENT LETHAL

CURRENTS TO PEOPLE?

ANSWER

NO !!!!!


4/44

HOME WIRING FUSES(SOL COND, 2000 V, ENCL SPACE)

15 A Fuse -

20 A Fuse -

25 A Fuse -

30 A Fuse -

#14 CU or #12 AL

#12 CU

#10 CU

FUSE SIZE WIRE PROTECTED

(1996 NECTables 310-16, 17, 18, 19, Footnotes)

#10 AL


5/44

BARE ACSR CONDUCTOR

CURRENT RATINGS(FREE AIR)

3/0 - 6/1 - 315 A

4/0 - 6/1 - 357 A

336 - 18/1 - 519 A

477 - 18/1 - 646 A

556 - 18/1 - 711 A

#6 - 6/1 - 105 A

#4 - 7/1 - 140 A

#2 - 7/1 - 184 A

1/0 - 6/1 - 242 A

2/0 - 6/1 - 276 A

COND RATING COND RATING

(SOUTHWIRE Overhead Conductor Manual; First Edition; Copyright 1994)


6/44

BARE COPPER CONDUCTOR

CURRENT RATINGS(FREE AIR)

1/0 - 7 STR - 311 A

2/0 - 7 STR - 360 A

3/0 - 7 STR - 417 A

4/0 - 7 STR - 482 A

#6 SOL - 128 A

#4 SOL - 170 A

#4 - 7 STR - 174 A

#2 SOL - 228 A

#2 - 7 STR - 233 A

COND RATING COND RATING

(SOUTHWIRE Overhead Conductor Manual; First Edition; Copyright 1994)


7/44

FUSE DEFINITION

An electronic device composed of a conductive element

(link) surrounded by a non-conductive filler, where the

element will melt and disintegrate at a designed current

level to open an electrical circuit.


8/44

FUSE

ELEMENT (LINK) DESIGN

Material = Silver, Tin, Copper, Nickel

or other Metal

Wire, bar or ribbon configuration witha designed weak point that melts at a

designed current level


9/44

Material = Silica Sand, Boric Acid,other non conductive or de-ionizing

substance Heat from arch, which occurs when

element melts, creates a nonconductive glass, or de-ionizing gas

that extinguishes the arc and stopscurrent flow

FUSE

FILLER MATERIAL


10/44

EXPULSION FUSE

OPERATION

Conductive element surrounded by looselypacked filler

Disintegrating element creates arc whichheats air to form conductive gas (Ozone)

Arc heats filler material which forms non-conductive gas

Non-Conductive gas expels conductive gas

and suffocates the arc Gas vented from fuse container to outside

Primary use in outdoor/indoor applications


11/44

NON - EXPULSION FUSE

OPERATION

Conductive Element surrounded in tightlypacked filler (silica sand) or vacuum

If sand filler - Heat from arc melts sandwhich turns to non-conductive glass

If Vacuum filler No air exist to create

Ozone so no conductive gas created No gas created / No Expulsion

Used in Indoor Applications and Current

Limiting fuses


12/44

Porcelain orComposite

Insulated Holder

Top Contact

Bottom Contact

with Link

Attachment and

Spring Lift

Fuse Link Inside

Fuse Tube

Fuse Link with

Button Head andPigtail

CUTOUTS

Fusible Switches / Replaceable Links


13/44

CUTOUT

Combination Power Disconnect Switchand replaceable fuse device

Hollow Fuse Holder lined with solid Arc

Quenching materialHouses Fuse Link

Produces non-ionizing gas when heated by

arcGas suffocates the arc vents out bottom

Expulsion Type Fuse


14/44

CUTOUT

Fuse Link2 Purposes in CutoutServes as Conducting Element

Size determines the Limit of Allowable Current

When Link melts Arc is created inside Holder

Provides Mechanical Tension to hold Switch

in Closed position

When Link melts Tension released and switchdrops open

Max Fuse Rating 200 Amp


15/44

CUTOUT

When Fuse Blows, Only Link is replaced

Cutout Use

Overhead Taps

Overhead Transformers

Overhead Capacitors

Underground Laterals


16/44

COOPER

Kearny McGraw Edison

HUBBELL - Chance

S&C

CUTOUT

Major Manufacturers


17/44

SMD 20 FUSE SWITCH


18/44


19/44

SMD 20 FUSE SWITCH

Fuse LinkServes as Conducting Element

Size determines the Limit of Allowable Current

When Link melts Arc is created inside Holder

Mechanically tied to Holder through arc rod

When Link melts gas pushes arc rod throughtop contact which drops SMU housing

Max Fuse Rating 200 Amp

When Fuse Blows - Replace Entire SMUHousing


20/44

ALL SMD Fuse Switches Have Same

Operating Process

SMD 1A, 2B, 2C and 3 Primary UsageSubstations

Rated 15 kV69 kV

Rated Current up to 300 AMP

SMD FUSE SWITCHES

S&COnly Manufacturer


21/44


22/44

BAYONET FUSES

High Side Fuse for Padmount Transformers

Switchgear

TYPES

Current Sensing

Dual Sensing

High Amp Overload

23 KV Max

USE in with High Current Protection

Internal Weak LinkLateral Fuse

Internal Current Limiting Fuse


23/44

BAYONET FUSE


24/44

BAYONET FUSE


25/44

BAYONET FUSE

Isolation Link or

Current Limiting Fuse


26/44

CURRENT LIMITING FUSE

High Fault FuseUsed in Conjunctionwith Low Fault Fuse

Non-Expulsion Fuse

Use

Padmount and Submersible Transformers

Indoor SwitchgearSome Dropout type Switches


27/44

CURRENT LIMITING FUSE


28/44


29/44

FUSE

TIME CURRENT CURVE

Seconds

Cycles

Amperes (common voltage 12.47 kV)

10 100 1000 10000 100000100000

0.010 0.6

0.10 6

1 60

10 600

100 6000

1000 600001000 60000

Fuse1

Type T-TIN 65 min melt

Fuse1

Type T-TIN 65 max c lear

65 T Fuse Link


30/44

TIME CURRENT CURVE

(65 K VS 65 T Link)

300 Amp Fault

65 K 65T

Start 1.30 sec 3.13sec

Clear 2.85 sec 7.11sec

1000 Amp Fault

65 K 65T

Start 0.08 sec 0.28 sec

Clear 0.14 sec 0.42 sec


31/44

3 TRANSFORMER


Protect Transformer from Secondary Faults

Protect Source Feed from

- Faults on Secondary

- Faults in the Transformer

Insure Fuse Wont Blow from

- Full Load of the Transformer

- Cold Load Pickup(610 x FL Amps)


32/44

3 TRANSFORMER



33/44

1 TRANSFORMER


Similar to 3 Phase Transformers

Protect Transformer from Secondary Faults

Protect Source Feed from

- Faults on Secondary

- Faults in the Transformer


34/44

1 TRANSFORMER


Insure Fuse Wont Blow from

- Full Load of the Transformer

- Cold Load Pickup ( 1.5 to 2 x FL Amps)

- Allow more Leniency in fusing due to

> Less Expensive Cost of unit

> More Customer Diversity


35/44

1 TRANSFORMER


25 KVA Transformer

7.2 KV - 120/240 V

Full Load = 25000VA/7200V = 3.47 A

Fuse Size = 1.5 x FL = 5.2 A

Fuse at 6 K or 6 T Link


36/44


37/44


38/44

1/0 ACSR good for 242 Amps

100 KVA @ 7200 V => 14 Amps

1.5 x (50 KVA/7.2 KV) = 10.4 Amp => 10K

25 KVA Fused at 6 K

F1 = ?

LINE TAP


LINE TAP


39/44

Additional 175 kVA Transformers

Total Maximum Tap Load = 39 Amps Largest transformer fuse 15 K

F1 = ?

F2 = ?

LINE TAP

FUSE COORDINATION


40/44

F3 = ?

F4 = ?

F5 = ?

LINE TAP

FUSE COORDINATION

# 4 ACSR good for 140 Amps


41/44


42/44

F3 = ?

F4 = ?

F5 = ?

R = ?

FUSE / RECLOSER

COORDINATION


43/44


44/44

POWER SYSTEM

FUSING SUMMARY

Fusing Protects Electrical Equipment

Transformers, Capacitors, Conductor

Isolates Faults on CircuitsLimits Number of Customers Affected

Hastens Identification of Affected area

Reduces Time of Outages

Improves System Operating Efficiency

Fusing Considerations by Brett Donjon Josh McGill

Documents

Transcript of Fusing Considerations by Brett Donjon Josh McGill