SEMI STEP Introduction to SEMI S 2 0706

SEMI STEP: Introduction to SEMI S 2 -0706 Short Circuit Current Rating Edward Karl Program Manager Corporate Product EHS Applied Materials 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Short Circuit Current Rating • NFPA 79 -2005, NFPA 70 -2005 (NEC), UL 508 A, and IEC 60204 -1 are turning their focus from interrupting capacity of the equipment's main overcurrent protective device, to short circuit current rating of the equipment (machine) industrial control panel. • In an effort to harmonize with changes in these standards, the nameplate criteria of SEMI S 2 and SEMI S 22 will be updated in July to include the short circuit current rating of the equipment or its industrial control panel. • SEMI S 2 and SEMI S 22 will also require that this information be in the equipment installation instructions. 2 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 NEC Compliance Map Source Reference: Square. D website http: //us. squared. com/us/products/motor_control. nsf/unid/BEABDD 3 D 2 C 1 FB 03 C 85256 EBE 0047 F 560/$file/ul 508 a. Frameset. htm 3 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Definitions • “Short circuit current rating” is defined in UL 508 A as "The prospective symmetrical fault current at a nominal voltage to which an apparatus or system is able to be connected without sustaining damage exceeding the defined acceptance criteria. " • “Short circuit current rating” is defined in SEMI S 2 -0706 and SEMI S 22 -0706 as "The maximum available current to which an equipment supply circuit is intended to be connected. " Speaker’s Note: The intent of the short circuit current rating is to provide end-users and AHJs with some idea of the maximum fault current the equipment is suitable of being connected. 4 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Impact To Semiconductor Industry • Per SEMI S 2 and SEMI S 22 (as well as the NEC, NFPA 79), every semiconductor manufacturing equipment will need to include the short circuit current rating of the equipment or its industrial control panel on the equipment nameplate. • As a result of NFPA 79 E regarding Arc Flash/Arc Blast requirements, some end-users are now discovering that their facilities may have available fault current that are greater than 10 KA. • NEC prohibits the installation of a system with industrial control panel with a lower short circuit current rating than the available fault current from the facility. • There is no standard or code specifying the maximum limit for available fault current at a facility. 5 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Challenges to Semiconductor Industry • Since the available fault current at user facilities may vary significantly, equipment suppliers are faced with the challenge of designing a reasonable SCCR for their products: Ø If the SCCR is too high, the cost and footprint of their products may increase. Ø If the SCCR is too low, their products may not be permitted to be connected to the users’ facilities (if the available fault current is higher). 6 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Methods of Determining Short Circuit Current Rating of an Industrial Control Panel I. Use a Listed UL 508 A Control Panel For a Listed UL 508 A Control Panel, the Short Circuit Current Rating would already be included in its nameplate. II. Conduct Short Circuit Testing Take a sample of the control panel and subject it to short circuit testing. III. Use UL 508 A Supplement SB Follow the method outlined in UL 508 A Supplement SB 7 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 UL 508 A, Supplement SB Method SB 4. 1. 1 The short circuit current rating of the overall industrial control panel shall be determined based upon: a) First, establishing the short circuit current ratings of individual power circuit components as specified in SB 4. 2. Exception: Power transformer, reactors, current transformers, dry-type capacitors, resistors, varistors, voltmeters, “S” contactor of a wye-delta motor controller and fire protection equipment are not required to have a SCCR (SB 4. 2. 1) b) Second, modify the available short circuit current within a portion of a circuit due to the presence of current limiting components as specified in SB 4. 3, when applicable; and c) Third, determining the overall panel short circuit current rating as specified in SB 4. 4. Note: Schneider Electric/Square. D has flowcharts on their website to assist manufacturers in determining Short Circuit Current of industrial control panel. 8 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Common Methods of Increasing SCCR Increasing Short Circuit Current Rating (SCCR) of an Industrial Control Panel can be achieved through: Ø Replacing or removing the lowest SCCR components with ones of higher SCCR. Ø Utilizing a Listed combination tested components that has an overall SCCR that is higher than that of the individual components. Ø Utilizing current limiting devices (e. g. , transformer, current limiting fuses, current limiting circuit breakers) Ø Empirically test the components or the entire industrial control panel to determine actual SCCR instead of using calculations. Ø Offer current limiting devices as user facility options to lower the available fault current to the equipment. 9 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Increasing SCCR of Industrial Control Panel Note: Information partly based on UL/Square. D presentation Listed SCCR Branch Circuit Combinations -SCCR listed with UL -Stand alone rating without feeder protection required - Branch Protection with Starters, contactors, Drives, Motor controllers - Has High Fault level Terminal block has generic SCCR of 10 k. A 10 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706 Example: Branch circuit Combination with SCCR of 22 k. A Removing the weakest link may increase the SCCR of the panel (to 22 k. A)

Introduction to SEMI S 2 -0706 Use of Isolation Power Transformers per UL 508 A, SB 4. 3. 1 Note: Information partly based on UL/Square. D presentation Circuit Breaker SCCR 10 k. A Isolation Transformer Circuit Breaker 20 k. A Contactor 5 k. A Overload Relay 5 k. A Terminal Block 10 k. A 11 12 July 2006 < 10 k. VA 5 k. A Note: • To be considered in the feeder circuit, must have secondary overcurrent protection • For a transformer rated 10 k. VA or less, the transformer secondary is assigned an available current of 5 k. A and all secondary side component in the power circuit must have a SCCR of 5 k. A or greater; on the primary side, only the SCCR of the primary overcurrent protection is considered relative to overall panel SCCR (ref. SB 4. 3. 1(a)) • No benefit for power transformer larger than 10 k. VA (ref SB 4. 3. 1(c) – the lowest short circuit current rating of the components in the secondary circuit is assigned to the line side of the power transformer circuit) Example: • 10 k. VA transformer with 10 k. A SCCR CB yields 10 k. A SCCR for this power circuit if all components on secondary side of transformer is at or above 5 k. A SCCR. SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Use of Current Limiting Feeder Circuit Breaker per UL 508 A, SB 4. 3. 2 Feeder “Current. Limiting” Circuit Breaker Contactor Note: Information partly based on UL/Square. D presentation Ip 5 k. A Note: • Max. let-through are not standardized for all Listed CBs; therefore, need to consult manufacturer’s let-through limits for specific CB. • SCCR on the line side of current limiting circuit breaker cannot exceed SCCR of any branch circuit protection • Peak current let-through of the current limiting CB cannot exceed the SCCR determined for any branch circuit on the load side. Example: • 5 k. A from Mfg’s Published let through (I peak only) Overload Relay Terminal Block 12 12 July 2006 • If the let through is less than the determined branch rating of the overall Short Circuit rating, it will be capable of connecting to available current per mfg’s let through chart or with fuses per table SB 4. 2. SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Use of Current Limiting Feeder Circuit Breaker Per UL 508 A, SB 4. 3. 3 Note: Information based on UL/Square. D presentation • Class CC, G, J, RK 1, RK 5, and T fuses are marked “Current Limiting” • Fuses must be in the feeder circuit • Peak current is found from Table SB 4. 2 based on fuse class and ampere rating. For fuses with ampere rating not in the table, use next higher ampere rating (for a 10 A Class CC fuse, use peak current for 15 A CC fuse) • SCCR on the line side of the current limiting fuses cannot exceed SCCR of any branch circuit protection • Peak current let-through of current limiting fuses cannot exceed the SCCR determined for any branch circuit on the load side. 13 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 UL 508 A, Supplement SBNote: Information partly based on UL/Square. D presentation SCCR of a control circuit is based on its overcurrent protection, not the SCCR of the control circuit components Circuit Breaker Contactor Fuse Overload Relay Control Transformer Terminal Block 14 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706 Control Circuit is a circuit that carries the electric signals directing the performance of a controller, and which does not carry the main power circuit. A control circuit is, in most cases, limited to 15 amperes, typically anything other than power circuit (e. g. , motor, heater, lights or appliance).

Introduction to SEMI S 2 -0706 Short Circuit Current Rating Questions? 15 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Excerpts from References Edward Karl Corporate Product EHS 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Excerpts from Referenced Documents 17 • NFPA 70 -2005, Article 670. 3(A) - Permanent Nameplate. The nameplate shall include the following information: (4) Short circuit current rating of the machine industrial control panel based on one of the following: a. Short circuit current rating of a listed and labeled machine control enclosure or assembly b. Short circuit current rating established utilizing an approved method. • NFPA 70 -2005, Article 409. 110 - Marking. An industrial control panel shall be marked with the following information that is plainly visible after installation: (3) Short-circuit current rating of the industrial control panel based on one of the following: a. Short-circuit current rating of a listed or labeled assembly b. Short-circuit current rating established utilizing an approved method (FPN: UL 508 A-2001, Supplement SB, is an example of an approved method). 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Excerpts from Referenced Documents 18 • NFPA 79 -2005 (Accepted Proposal), Section 16. 4. 1 (currently 17. 4. 1) Machine Nameplate Data. A nameplate giving the following information shall be attached to the enclosure: (6) Short-circuit current rating of the control panel. • SEMI S 2 -0706, Section 13. 4. 12 – A permanent nameplate listing the manufacturer’s name, machine serial number, supply voltage, phase frequency, short circuit current rating of the equipment or its industrial control panel and… • SEMI S 22 -0706, Section 20. 4 i) – Equipment Nameplate – A permanent nameplate should be attached to the main electrical enclosure or equipment where it is plainly visible after installation. This nameplate should include the following information: i) short-circuit current rating of the equipment or its industrial control panel… 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706

Introduction to SEMI S 2 -0706 Excerpts from Referenced Documents 19 • UL 508 A, First Edition, April 25, 2001 (revised through May 1, 2003) – 52. 1 An industrial control panel shall be provided with a nameplate that includes the following: b) Complete electrical rating of each source of supply as specified in 49. 1 – 49. 5 The input terminals in 49. 1 shall have a short circuit current rating. The short circuit rating shall be based on the requirements in Supplement SB. (Effective April 25, 2006). • IEC 60204 -1 (2005), Clause 16. 4 - Marking of equipment. Equipment (for example control gear assemblies) shall be legibly and durably marked in a way that is plainly visible after the equipment is installed. A nameplate giving the following information shall be attached to the enclosure adjacent to each incoming supply: … - short-circuit rating of the equipment; … 12 July 2006 SEMI STEP: Introduction to SEMI S 2 -0706