1. I believe NEC requires all 120V 15A branch circuits with 5015 receptacles to be branch circuit protected so the UL 1077 breaker should be fine. Outside of NEC may be another matter. 2/3. If Inverter, Frequency Drive, PWM Motor Controller provides overload protection (they usually do) then the supplemental protector should be fine as long as it's preceded by branch circuit protection. But I don't think the supplemental protector can provide any motor overload protection by itself.
Your product should probably be design/tested/listed to its own applicable standard. NFPA 70 430 would be for motors installed into a building as part of a general construction project. It would not apply to a separately tested/listed portable product plugged into the wall. -Dave -----Original Message----- From: Kunde, Brian [mailto:[email protected]] Sent: Friday, March 10, 2017 1:49 PM To: [email protected] Subject: [PSES] Moter Overload Protection with Supplemental Protector Greetings experts. This question applies to both North America rules (NEC) keeping in mind the rest of the world including Europe BUT my example will be for a 115Vac 60hz device. My example product is used in the Workplace but not typically in an industrial environment (if that matters). It's not a home appliance or power tool. Consider an End Product powered by 115Vac 60hz from a standard 16AWG power cord with a NEMA-5-15 plug, from a 15 amp receptacle (15 amp Branch Circuit). Within this product is a 1/2 hp motor with an Full-Load Amp (FLA) rating of 5 amp. The motor can run continuous in this application. The motor does not have integrated over temperature protection. Scenario 1: If this was a single phase AC motor, we would have to provide Overload Protection. According to the NEC, a fuse or circuit breaker no larger than 6.25 amp (FLA x 125%) can be used (lets ignore start up current for now). Can this Overload Protector be a "Supplemental Protector" (UL 1077 circuit breaker) or does it have to be a UL 489 circuit breaker or some other type of device? Scenario 2: If an Inverter, Frequency Drive, PWM Motor Controller, etc. is used to drive an AC or PWM DC motor (1/2hp), the Branch Circuit is not stressed by Motor Start currents since the motor is soft started. So for example, if we have a 1/2hp 90Vdc motor that is driven by a PWM controller, can the Overload Protector be a Supplemental Protector? If not, what does it have to be and why? Scenario 3: If the inverter, frequency drive, PWN motor controller, etc. provides Overload Protection for the motor, do we even need to add an additional Overload protector? Can we use a single Supplemental protector for the entire product and not worry about the motor? In this scenario, I assume the motor controller would have to be Listed by a safety agency and specifically call out the overload protection feature in the datasheet. What other concerns might I need to know about? I'm trying to make sense of the NEC article 430 but it doesn't seem to address motors driven by Motor Controllers. Can I assume that when a motor is driven by a Motor Controller (inverter, freq. drive, PWM, etc.) that the NEC 430 does not apply because the motor is not being directly powered by a Branch Circuit? Thanks to all in advance. The Other Brian ________________________________ LECO Corporation Notice: This communication may contain confidential information intended for the named recipient(s) only. If you received this by mistake, please destroy it and notify us of the error. Thank you. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
