Interrupting Rating
advertisement
Device Basics & Important Criteria Hershey Feldstein It’s simple 한국조달, 052-227-8325, http://hankookjodal.com WHY DO FUSES EXIST To Help Prevent Electrical Fires. Electrical Explosions. To Help Protect People from injury due to fires and explosions. Electrical/Electronic Equipment. The customers investment in the above. 한국조달, 052-227-8325, http://hankookjodal.com WHERE ARE FUSES USED Factory/Office Buildings Machines/Motors Air Conditioners Lighting Circuits Computers Power Supplies Automobiles Rapid Transit (Metro-Link, BART, etc.) Telecommunication Transmission Utility Generation 한국조달, 052-227-8325, http://hankookjodal.com OVERCURRENTS Any current in excess of the rated current of the equipment, the ampacity of a conductor, or the circuit Overload Short-circuit (fault) 한국조달, 052-227-8325, http://hankookjodal.com TYPES OF OVERCURRENTS OVERLOAD Current in excess of the normal, full-load rating, that when it exists for a sufficient period of time, will cause damage or dangerous overheating. Within normal path 한국조달, 052-227-8325, http://hankookjodal.com 한국조달, 052-227-8325, http://hankookjodal.com TYPES OF OVERCURRENTS SHORT-CIRCUIT An overcurrent, typically many times larger than the normal operating current. Outside of normal path 한국조달, 052-227-8325, http://hankookjodal.com Short Circuit VS R R Source R ISC= VS / RT Load R R R R Out of the circuit Outside the normal path 한국조달, 052-227-8325, http://hankookjodal.com 한국조달, 052-227-8325, http://hankookjodal.com TYPICAL SHORT CIRCUIT CURRENTS • • • • • • • • Home Receptacle - 200 to 500 amps Home Service - 2,000 to 10,000 amps Bussmann Headquarters - 70,000 amps New York City - 202,000 amps St. Louis, MO - 210,000 Chicago, IL - 215,000 Dallas, TX - 220,000 Tulsa, Oklahoma - 260,000 amps 한국조달, 052-227-8325, http://hankookjodal.com Overcurrent Protection… …is like insurance. You hope you never need it… But when you do, you want the best ! 한국조달, 052-227-8325, http://hankookjodal.com What will be covered Overcurrent Protective Devices Criteria: Overcurrent Protection Other Typical Components 한국조달, 052-227-8325, http://hankookjodal.com Review Device Types Mechanical overcurrent protective devices, listed for: • Overload & short-circuit (thermal mag CB) • Short-circuit only (MCP) • Overload only (overload relays & MMS) • Overload & short-circuit (self protected starters) Fuses • Overload & short-circuit • Short-circuit only 한국조달, 052-227-8325, http://hankookjodal.com Mechanical OCPDs Common Characteristics: current sensing means unlatching means contact parting means 한국조달, 052-227-8325, http://hankookjodal.com Common Characteristics: current sensing means unlatching means contact parting means 한국조달, 052-227-8325, http://hankookjodal.com Magnetic Element Bimetal Trip Bar Circuit Breaker Operation Load Line Latch 한국조달, 052-227-8325, http://hankookjodal.com Spring Loaded Contacts Magnetic Element Bimetal Trip Bar Thermal Overload Operation Unlatches Opens Load Line Latch 한국조달, 052-227-8325, http://hankookjodal.com Spring Loaded Contacts Magnetic Element Bimetal Trip Bar Short Circuit Operation Unlatches Contacts Part & Arcing Load Line Latch 한국조달, 052-227-8325, http://hankookjodal.com Spring Loaded Contacts Thermal Magnetic Circuit Breakers SPD P. 55 Thermal Magnetic Molded Case Circuit Breaker TimeCurrent Curve Overload Region Instantaneous Region Interrupting Time Unlatching Time Interrupting Rating 한국조달, 052-227-8325, http://hankookjodal.com Modern Current- Limiting Fuses Fuse: Simple, reliable Based on thermal principle 한국조달, 052-227-8325, http://hankookjodal.com Fuse Characteristics Time vs Current curves show how long it will take for a fuse to open given a specific current level. Current limiting effect charts and curves show the amount of current a fuse will let through when clearing a fault. (later in presentation) 한국조달, 052-227-8325, http://hankookjodal.com Fuse Time Current Curves 한국조달, 052-227-8325, http://hankookjodal.com SPD P. 51 Fuse Characteristics Non time delay (NON/S - Limiters) Fast acting (JJN/S, KWN/S, KTN/S) Time Delay (KRP-C) Dual-element, time delay (LPS/N,FRN/S, LPJ) High speed (semiconductor protection) 한국조달, 052-227-8325, http://hankookjodal.com Fuse Element Basics Element Melting Degrees F Zinc 788 Silver AG / M Tin Spot 1763 550 Copper CU / M Tin spot 1981 600 Dual Element Fusing Alloy 한국조달, 052-227-8325, http://hankookjodal.com 285 FAST ACTING FUSES Fast acting fuses are typically only used in circuits without an inrush current. Lighting & Heating 한국조달, 052-227-8325, http://hankookjodal.com TIME DELAY FUSES Time delay fuses allow temporary and harmless inrush currents from motors, transformers and other sources to pass without opening the circuit. 한국조달, 052-227-8325, http://hankookjodal.com Fuse Construction Dual Element Time-Delay • Designed to be sized close to load and accommodate motor and transformer inrush which could not be accomplished by single-element nontime-delay or fast-acting fuses. • Overload (time delay) Element • Short Circuit (current limitation) Element 한국조달, 052-227-8325, http://hankookjodal.com Dual Element Fuse Element Small volume of metal to vaporize Short–circuit element Overload Element Short-circuit operation filler quenches arc 한국조달, 052-227-8325, http://hankookjodal.com Overload Operation SPD p.15 Before Dual Element Time-Delay • Under sustained overload condition, spring operated trigger assembly separates the “connector” from the shortcircuit element, opening the circuit. After 한국조달, 052-227-8325, http://hankookjodal.com Short-Circuit Operation Dual Element TimeDelay • Under a short-circuit condition, restricted portions of the shortcircuit element melt and arc to burn back the resulting gaps until the arcs are suppressed by the arc quenching material and increased arc resistance. 한국조달, 052-227-8325, http://hankookjodal.com Buss Dual-Element Fuses • Sustain Harmless Overloads • Size Close to Loads • Save on Switch Size • Provide Better Protection 한국조달, 052-227-8325, http://hankookjodal.com Major Fuse Advantage Simple, reliable operating principal. Factory calibrated replacements after an overcurrent. No required maintenance. 한국조달, 052-227-8325, http://hankookjodal.com Criteria That Might Be Very Important Ampere rating System voltage & device voltage ratings Interrupting rating(s) Current-limitation Selective coordination Protection of components 한국조달, 052-227-8325, http://hankookjodal.com Criteria That Might Be Very Important Reliability Maintenance practices Worker Safety • Arc Flash • Shock Size Cost 한국조달, 052-227-8325, http://hankookjodal.com Ampere Rating LPS-RK 30 SP I L=40 Amps 600 Volt fuse LOAD 480 Volt Improper Application 한국조달, 052-227-8325, http://hankookjodal.com Ampere Rating LPS-RK 50 SP I L=40 Amps 600 Volt fuse 480 Volt Correct Application 한국조달, 052-227-8325, http://hankookjodal.com LOAD Voltage Ratings Several Voltage Considerations • General OCPD Rating / system voltage • Creepage & clearance capabilities • AC/DC • Slash ratings i.e. 480Y/277 한국조달, 052-227-8325, http://hankookjodal.com Voltage Rating LPN-RK 30 SP 250 Volt Rated Fuse LOAD 480 VOLTS Improper Application 한국조달, 052-227-8325, http://hankookjodal.com Voltage Rating LPS-RK 30 SP 600 Volt fuse 480 Volt Correct Application 한국조달, 052-227-8325, http://hankookjodal.com LOAD Voltage AC / DC Overcurrent protective devices can be rated for AC only, DC only, AC / DC. AC rating is not necessarily equal to DC rating Some OEMs & MROs have DC applications Be sure to use properly rated overcurrent protective devices. Ask about the time-constant 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating What is this??? The maximum amount of current a device can safely clear at rated voltage. 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating 480 Volt 600 Volt fuse 10,000 A IR 50,000A Available Violation 110.9 한국조달, 052-227-8325, http://hankookjodal.com LOAD Interrupting Rating OCPD with improper Interrupting Rating 10,000A IR, 600V, Class H Fuse 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 10,000A IR, 600V, Class H Fuse 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 10,000A IR, 600V, Class H Fuse 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 10,000A IR, 600V, Class H Fuse 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 10,000A IR, 600V, Class H Fuse 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 10,000A IR, 600V, Class H Fuse 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating L 480 V Circuit Breaker 14,000 A IR 480 Volt 50,000A Available Violation 110.9 한국조달, 052-227-8325, http://hankookjodal.com LOAD Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating OCPD with improper Interrupting Rating 14,000A IR, 480V, Circuit Breaker 50,000 Available 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating LPS-RK 50 SP I L=40 Amps 480 Volt 600 Volt fuse 300,000 A IR 50,000 A AVAILABLE Complies with 110.9 한국조달, 052-227-8325, http://hankookjodal.com LOAD Select OCPD’s with I.R. equal to or greater than shortcircuit current available at each point of application 300,000 Amp Interrupting Rating 한국조달, 052-227-8325, http://hankookjodal.com Interrupting Rating Fuses: 300,000 A.I.R. / Isca = 50,000 A Before After Proper Interrupting Rating With Fuses – No Violence 한국조달, 052-227-8325, http://hankookjodal.com Major Fuse Advantage Interrupting Rating Modern current limiting fuses typically can be applied without concern of exceeding the fuse interrupting rating ! 한국조달, 052-227-8325, http://hankookjodal.com Short Circuit Current Asymmetrical Degree asymmetry • Power factor • Point on cycle when initiated Normal Load Current Fault Occurs At this Time 한국조달, 052-227-8325, http://hankookjodal.com Fault Current Noncurrent-limiting 2 ½ cycle opening Current-limiting less than 1/2 cycle opening 1/4 cycle opening cy opening 11cycle 한국조달, 052-227-8325, http://hankookjodal.com Current-limitation SPD P. 71 한국조달, 052-227-8325, http://hankookjodal.com Current-limitation SPD P. 72 한국조달, 052-227-8325, http://hankookjodal.com Typical Circuit Components Insulated conductors Switches Motors Starters Contactors Transformers Coils Heating elements 한국조달, 052-227-8325, http://hankookjodal.com Capacitors Busway Lighting fixtures Semiconductor devices Motor control centers Lighting panels Panelboards Switchboards Lacking Coordination Selective Coordination OPENS NOT AFFECTED OPENS UNNECESSARY POWER LOSS NOT AFFECTED 한국조달, 052-227-8325, http://hankookjodal.com Fault Fault Selective Coordination Modern current-limiting fuses assure selective coordination. Simply use amp rating ratios Typically 2:1 for Low Peak to Low Peak 한국조달, 052-227-8325, http://hankookjodal.com Selective Coordination SPD P. 52 Line Side Fuse Load Side Fuse LOW-PEAK® : LOW-PEAK® 2:1 Line:Load Ratio Selectivity Ratio Table Assures Coordination! No Plotting required! 한국조달, 052-227-8325, http://hankookjodal.com Lacking Coordination Selective Coordination 125 OPENS 400 NOT AFFECTED UNNECESSARY POWER LOSS 한국조달, 052-227-8325, http://hankookjodal.com 90 Fault 60 OPENS NOT AFFECTED 30 Fault Thermal Magnetic Circuit Breakers 90A & 400A Molded Case Circuit Breakers Inherent long delay between unlatching and interrupting due to mechanical means of breaking current Upstream breaker can unlatch before the downstream breaker can clear the fault Lack of Selective Coordination in the Short-Circuit Region 한국조달, 052-227-8325, http://hankookjodal.com SPD. 56 Major Fuse Advantage Modern Current Limiting Fuses offer: Best current limitation to provide exellent component protection under short-circuit conditions. Easy coordination using published ratios. 한국조달, 052-227-8325, http://hankookjodal.com Fuse Characteristics SPD P. 19-21 Voltage Ratings Ampere Rating Range For Family Ampere Rating Case Size Interrupting Rating UL Class - Degree of current-limitation Physical Size Termination Methods Branch Circuit or Supplementary Protection Special Purpose Applications 한국조달, 052-227-8325, http://hankookjodal.com There is a difference Fuses Circuit Breakers Simple & Reliable Factory Calibrated Replacements High Interrupting Rating Current-limiting Protect Components Selective Coordination No Maintenance 한국조달, 052-227-8325, http://hankookjodal.com Mechanical Device After Fault Must Be Tested & Maybe Replaced More Cost For Higher Interrupting Ratings Typically Not CurrentLimiting – Higher Cost Typically Not Coordinated Periodic Maintenance Required & Possible Replacement OSHA Does Not Permit Resetting Into Fault
