Surge Protection for CNC Turning Center
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| CNC Turning Center |
The latest release of NEC/NFPA 70 edition 2020 (NEC 2020) has placed a greater emphasis on increasing personnel safety by mandating the use of Surge Protective Devices (SPDs).
From 2014 to 2020, the number articles now requiring SPDs has increased significantly for applications ranging from Modular Data Centers, Fire Pumps, Elevators, Critical Power Systems, Dwellings (Dormatories, Homes, Hospitals, Hotels), etc.
Threat to industrial machines
Various codes and standards possess safety interlock criteria including the American National Standards Institute (ANSI) standards and NFPA 79 for Industrial Machinery. However, until now, these standards have only just begun to address the expanding role that surge protection plays preserving the integrity of equipment and, more importantly, protecting the lives of personnel.
A study commissioned by the Fire Protection Research Foundation, “Data Assessment for Electrical Surge Protective Devices”, provides results of a survey of facility managers concerning surge damage. (NFPA 2014) The study shows that 26 percent of facility managers had damage to safety interlocking systems on industrial machines due to surges . The main purpose of these safety interlocking systems is to protect workers and maintenance personnel from contact with exposed live parts and electric shock. Failure of these devices can put personnel at an increased risk of injury.
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| CNC lathe |
The solution for NFPA 70 and NFPA 79
To make the installation of a Surge Protective Device (SPD) at the industrial machines interlocking safety circuit mandatory which in turn increases the equipments reliability.
| NFPA 70 Article 670.6 Surge Protection. |
| "Industrial machinery with safety inter-lock circuits shall have surge protection installed.” |
In addition, the NFPA 79 is now requiring the following changes:
| 7.8.1 Surge Protective Devices (SPDs). |
| "Industrial machinery with safety circuits not effetively protected from the effects of overvoltages due to lightning or switching surges shall have surge protection installed. SPDs shall not be required where the risks associated with the effects of overvoltages are mitigated such that the safety performance determined by a risk assessment is met.” |
as well as
| 4.5.2 Electromagnetic Compatibility (EMC). |
| "Transient suppression, isolation, or other appropriate means shall be provided where the equipment of an industrial machine generates electrical noise or transients, which can affect the operation of equipment that is on or part of the industrial machine." |
Selecting an SPD for Industrial Machinery
NEC/NFPA 70 require that Surge Protective Devices (SPDs) shall be UL1449 Listed . This means selecting a surge protector is easier than it has ever been. There are only a few choices available for SPDs that are UL Listed for any of the most commonly used surge standards including UL1449 5th Edition, UL497B, and UL497E.
Recommended SPD for Industrial Machines
| Location | Equipment | System | Surge Protector Model# | Link |
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| Service Entrance | Main Service Panelboard | 277/480Vac | MDS750E-277Y |
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| Branch Panel | Equipment Panelboard | 480Vac | ${ITEM_LINK#2178948}<-No Item, #2178948 M50-480D-A | ${ITEM_LINK#2178948}<-No Item, #2178948
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| Local Equipment | Control Panel | 480Vac Power Input | DS74US-480D |
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| Power Supply | 120-240Vac Power Input | DS72US-230S/G |
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| 24Vdc Power Output | DS220S-24DC |
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| Control Unit | Ethernet Cat 6A | MJ8-C6A |
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| 4-20mA | DLA-24D3 |
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| Wireless | P8AX09-6G-N/FF |
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Types of machines covered by NFPA 79
| Type | Description |
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| Machine Tools | Metal Cutting Metal Forming |
| Plastics Machinery | Injection molding machines Extrusion machinery Blow molding machines Specialized processing machines Thermostat molding machines Size reduction equipment |
| Wood Machinery | Woodworking machinery Laminating machinery Sawmill machinery |
| Material-Handling Machinery | Industrial robots Transfer machines Sortation machines |
| Inspection/Testing Machines | Coordinate measuring machines In-process gauging machines |
| Packaging Machines | Carton-strapping machines Drum-filling machines Palletizing machines |
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| 10108 USA Today Way Miramar, FL 33025 USA | Contact us to develop a surge mitigation solution for your application |
| www.citel.us | Where to purchase Citel SPD's |
Standard and Electric Code References for Surge Protective Devices
| # | Title |
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| 1 | NFPA 70 edition 2020, Article 670 Industrial Machinery, 670.6 Surge Protection |
| 2 | NFPA 70 edition 2017, Article 670 Industrial Machinery, 670.6 Surge Protection |
| 3 | NFPA 70 edition 2014, “Data Assessment for Electrical Surge Protective Devices” |
| 4 | NFPA 79 edition 2021, Electrical Standard for Industrial Machinery, Chapter 7, 7.8 Protection Against Overvoltages Due to Lightning and Switching Surges 7.8.1 Surge Protective Devices (SPDs) |
| 5 | NFPA 79 edition 2018, Annex C, Examples of Industrial Machines Covered by NFPA79 |
| 6 | ANSI C62.41, Low-Voltage AC Power Circuits |
| 7 | UL1449 4th Edition, Surge Protective Devices |
| 8 | UL1449 5th Edition, Surge Protective Devices |
| 9 | UL497B, Surge Protectors for Data Lines and Fire-Alarm Circuits |
| 10 | UL497E, Antenna Lead-in Conductors |
| 11 | IEC 61643-11, Low-Voltage Surge Protective Devices - Part 11: Surge Protective Devices Connected To Low-Voltage Power Systems - Requirements And Test Methods |
| 12 | IEC 61643-21, Low Voltage Surge Protective Devices - Part 21: Surge Protective Devices Connected To Telecommunications And Signalling Networks - Performance Requirements And Testing Methods |
| 13 | IEC 61000-45, Electromagnetic Compatibility (EMC) - Part 4-5: Testing And Measurement Techniques - Surge Immunity Test |
| 14 | CSA 22.2 |
| 15 | NOM-001-SCFI, Standard for Electronic Equipment |
| 16 | NOM-003-SCFI, Electrical Products - Safety Requirements |
| 17 | SEMI S22, Safety Guideline for the Electrical Design of Semiconductor Manufacturing Equipment |
