RE: Are NTCs Safe to Use in Electrical Equipment
Personally . . . my take on this specific issue is to find the cause NOT treat the symptom . . . there is (obviously) something wrong there. I wouldn't put my family (or myself) at risk doing something like adding NTCs in my house wiring when that's not a normal thing to do . . . That's my personal opinion . . . John Juhasz Fiber Options Bohemia, NY -Original Message- From: Peter Tarver [mailto:ptar...@nortelnetworks.com] Sent: Thursday, July 20, 2000 11:01 AM To: Jim Eichner; emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment I really don't have a clear idea of whether or not your solution will work. Let us know. NTCs, as with most thermistors, get very hot when in their switched state. For the NTC, that's it's steady-state condition. I wouldn't put this in a junction box with other wiring, unless you're absolutely certain all the wiring can take the temperatures they'll encounter (for normal household wiring, likely not). Rather, for the sake of your experiment, put the NTC in a separate (probably should be metal) box that's in-line with the receptacle, with appropriate goesintas and goesouttas. Be certain to use your best safety engineer's hat for this activity. Regards, Peter L. Tarver, PE Homologation Engineering Nortel Networks ptar...@nortelnetworks.com -Original Message- From: Jim Eichner [ mailto:jim.eich...@xantrex.com <mailto:jim.eich...@xantrex.com> ] Sent: Monday, July 10, 2000 11:35 AM To: emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment On the subject of NTC's, please allow me a slight detour from the compliance world to the real world. I have a circuit in my house that blows light bulbs far more often than any other. I can't determine any reason for this - the voltage seems normal and there aren't any transient-producers on that same circuit (that I'm aware of). Long life and rural-duty bulbs make little or no difference. Instead of figuring out the root cause, I'm considering resorting to trying to deal with the symptom (blown bulbs) by putting an NTC in series with the light fixture somewhere. My thinking is that the mechanism that blows an incandescent bulb filament is related to the high inrush current into the cold (and therefore low R) filament, and the physical and thermal stresses that that inrush causes. Any comments on how likely this is to help, and whether or not I can safely put an NTC in an junction box full of wires? I'd check the NTC's temperature under load (they get hot) and compare that the the temp. rating of the wires in the box. I'd also insulate the bare legs of the NTC and try to make sure it isn't touching anything else. Anyone familiar with the failure modes of these things? Thanks, Jim -Original Message- From: Peter Merguerian [ mailto:pmerguer...@itl.co.il <mailto:pmerguer...@itl.co.il> ] Sent: Monday, July 10, 2000 7:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il <http://www.itl.co.il> --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Are NTCs Safe to Use in Electrical Equipment
Peter - Thermistors are in common usage and my limited experience with them indicates they are reliable for their intended function. The thermal issues have been discussed, and the usual regimen for high temperature components applies. I'm not aware of any other particular safety concerns. There are some NTC is UL's RCD, under Thermistor Type Devices (XGPU2). I don't know about certifications with other agencies or for other countries. Regards, Peter L. Tarver, PE Homologation Engineering Nortel Networks ptar...@nortelnetworks.com -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Monday, July 10, 2000 7:58 AM To: emc-pstc Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Are NTCs Safe to Use in Electrical Equipment
I really don't have a clear idea of whether or not your solution will work. Let us know. NTCs, as with most thermistors, get very hot when in their switched state. For the NTC, that's it's steady-state condition. I wouldn't put this in a junction box with other wiring, unless you're absolutely certain all the wiring can take the temperatures they'll encounter (for normal household wiring, likely not). Rather, for the sake of your experiment, put the NTC in a separate (probably should be metal) box that's in-line with the receptacle, with appropriate goesintas and goesouttas. Be certain to use your best safety engineer's hat for this activity. Regards, Peter L. Tarver, PE Homologation Engineering Nortel Networks ptar...@nortelnetworks.com -Original Message- From: Jim Eichner [mailto:jim.eich...@xantrex.com] Sent: Monday, July 10, 2000 11:35 AM To: emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment On the subject of NTC's, please allow me a slight detour from the compliance world to the real world. I have a circuit in my house that blows light bulbs far more often than any other. I can't determine any reason for this - the voltage seems normal and there aren't any transient-producers on that same circuit (that I'm aware of). Long life and rural-duty bulbs make little or no difference. Instead of figuring out the root cause, I'm considering resorting to trying to deal with the symptom (blown bulbs) by putting an NTC in series with the light fixture somewhere. My thinking is that the mechanism that blows an incandescent bulb filament is related to the high inrush current into the cold (and therefore low R) filament, and the physical and thermal stresses that that inrush causes. Any comments on how likely this is to help, and whether or not I can safely put an NTC in an junction box full of wires? I'd check the NTC's temperature under load (they get hot) and compare that the the temp. rating of the wires in the box. I'd also insulate the bare legs of the NTC and try to make sure it isn't touching anything else. Anyone familiar with the failure modes of these things? Thanks, Jim -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Monday, July 10, 2000 7:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Are NTCs Safe to Use in Electrical Equipment
Jim, Replacing the switch with a toggle type dimmer will greatly lengthen the service life of bulbs. I have them in bedrooms and the bathroom. The main intent was to prevent being jolted awake by bright lights if it were necessary to get up at night. Because they look like ordinary light switches, visitors have no trouble operating them. As to using NTC thermistors, I would recommend that you NOT use them inside of an electrical box. They do get quite hot, and even if they did not damage wire insulation, you might be risking your insurance coverage in the event of a fire. I have used them in the past to reduce inrush currents in power supplies, but these were forced air cooled. Without forced cooling, they provide almost no protection if power is re-applied almost immediately after shutoff. By the way, mechanical vibration may be the real culprit. I used to work in a place where the bulbs failed with alarming frequency in our old shield room. Leaving the ventilation blower off reduced the failure rate. Fragile filaments hate to be shaken. Scott Lacey -Original Message- From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf Of Jim Eichner Sent: Monday, July 10, 2000 2:35 PM To: emc-p...@majordomo.ieee.org Subject: RE: Are NTCs Safe to Use in Electrical Equipment On the subject of NTC's, please allow me a slight detour from the compliance world to the real world. I have a circuit in my house that blows light bulbs far more often than any other. I can't determine any reason for this - the voltage seems normal and there aren't any transient-producers on that same circuit (that I'm aware of). Long life and rural-duty bulbs make little or no difference. Instead of figuring out the root cause, I'm considering resorting to trying to deal with the symptom (blown bulbs) by putting an NTC in series with the light fixture somewhere. My thinking is that the mechanism that blows an incandescent bulb filament is related to the high inrush current into the cold (and therefore low R) filament, and the physical and thermal stresses that that inrush causes. Any comments on how likely this is to help, and whether or not I can safely put an NTC in an junction box full of wires? I'd check the NTC's temperature under load (they get hot) and compare that the the temp. rating of the wires in the box. I'd also insulate the bare legs of the NTC and try to make sure it isn't touching anything else. Anyone familiar with the failure modes of these things? Thanks, Jim -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Monday, July 10, 2000 7:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Are NTCs Safe to Use in Electrical Equipment-short life of li ght bulbs
In the spirit of trying the simplest thing first, I'll swap the light switch out for a new one and see what happens. Thanks for the tip, Jim -Original Message- From: Robert Macy [mailto:m...@california.com] Sent: Monday, July 10, 2000 12:49 PM To: Jim Eichner; emc-p...@majordomo.ieee.org Subject: Re: Are NTCs Safe to Use in Electrical Equipment-short life of light bulbs The subject of short life of light bulbs appears often on the alt.home.repairnewsgroup. People come up with potential sources of problems like "on the same branch with the sump pump(or well pump)", and "long lines to the light bulb". Their solutions were to put in those dimmer switches that cause the light bulb to only get power at crossover "gently" turning them on. And "lower the voltage", and ... but the consensus of the true source of short lived light bulbs is "either a poor neutral termination or the light switch needs to be replaced!" I thought this a suspect answer until after this experience. My bathroom fixture took out light bulbs at the rate of about 1 per month, but that made sense with the concentration of heat inside its housing and with the ON/OFF cycling it is subjected to. Then one day the switch jammed up and had to be replaced. After that replacement, the fixture will keep bulbs for almost a year. Evidently, the "bouncing" contacts really do a trip on the cold filaments. You might be right in that an NTC (Negative Temperature Coefficient Resistor) will make up for it. But it hardly seems worth the effort. (Plus if it's not the switch, a potential of a poor neutral could really mean a major problem in your system. ) - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Jim Eichner To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Monday, July 10, 2000 12:22 PM Subject: RE: Are NTCs Safe to Use in Electrical Equipment > >On the subject of NTC's, please allow me a slight detour from the compliance >world to the real world. > >I have a circuit in my house that blows light bulbs far more often than any >other. I can't determine any reason for this - the voltage seems normal and >there aren't any transient-producers on that same circuit (that I'm aware >of). Long life and rural-duty bulbs make little or no difference. > >Instead of figuring out the root cause, I'm considering resorting to trying >to deal with the symptom (blown bulbs) by putting an NTC in series with the >light fixture somewhere. My thinking is that the mechanism that blows an >incandescent bulb filament is related to the high inrush current into the >cold (and therefore low R) filament, and the physical and thermal stresses >that that inrush causes. > >Any comments on how likely this is to help, and whether or not I can safely >put an NTC in an junction box full of wires? I'd check the NTC's >temperature under load (they get hot) and compare that the the temp. rating >of the wires in the box. I'd also insulate the bare legs of the NTC and try >to make sure it isn't touching anything else. Anyone familiar with the >failure modes of these things? > >Thanks, > >Jim > >-Original Message- >From: Peter Merguerian [mailto:pmerguer...@itl.co.il] >Sent: Monday, July 10, 2000 7:58 AM >To: emc-p...@majordomo.ieee.org >Subject: Are NTCs Safe to Use in Electrical Equipment > > > >Dear All, > >I have seen some design where NTCs are used to limit inrush currents in >motion controllers. > >Q. Are NTCs safe and reliable as means to limit inrush currents? > >Q. Are there safety considerations to consider for circuits employing NTCs? > >Q. Are there any Approved (previously evaluated) NTC components out there? > > >I appreciate all of your comments and/or links regarding the use of NTCs in >electrical equipment. > >Thanks > >Peter Merguerian >Managing Director >Product Testing Division >I.T.L. (Product Testing) Ltd. >Hacharoshet 26, POB 211 >Or Yehuda 60251, Israel > >Tel: 972-3-5339022 Fax: 972-3-5339019 >e-mail: pmerguer...@itl.co.il >website: http://www.itl.co.il > > > > > > >--- >This message is from the IEEE EMC Society Product Safety >Technical Committee emc-pstc discussion list. > >To cancel your subscription, send mail to: > majord...@ieee.org >with the single line: > unsubscribe emc-pstc > >For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail
Re: Are NTCs Safe to Use in Electrical Equipment-short life of light bulbs
The subject of short life of light bulbs appears often on the alt.home.repairnewsgroup. People come up with potential sources of problems like "on the same branch with the sump pump(or well pump)", and "long lines to the light bulb". Their solutions were to put in those dimmer switches that cause the light bulb to only get power at crossover "gently" turning them on. And "lower the voltage", and ... but the consensus of the true source of short lived light bulbs is "either a poor neutral termination or the light switch needs to be replaced!" I thought this a suspect answer until after this experience. My bathroom fixture took out light bulbs at the rate of about 1 per month, but that made sense with the concentration of heat inside its housing and with the ON/OFF cycling it is subjected to. Then one day the switch jammed up and had to be replaced. After that replacement, the fixture will keep bulbs for almost a year. Evidently, the "bouncing" contacts really do a trip on the cold filaments. You might be right in that an NTC (Negative Temperature Coefficient Resistor) will make up for it. But it hardly seems worth the effort. (Plus if it's not the switch, a potential of a poor neutral could really mean a major problem in your system. ) - Robert - Robert A. Macy, PEm...@california.com 408 286 3985 fx 408 297 9121 AJM International Electronics Consultants 619 North First St, San Jose, CA 95112 -Original Message- From: Jim Eichner To: emc-p...@majordomo.ieee.org List-Post: emc-pstc@listserv.ieee.org Date: Monday, July 10, 2000 12:22 PM Subject: RE: Are NTCs Safe to Use in Electrical Equipment > >On the subject of NTC's, please allow me a slight detour from the compliance >world to the real world. > >I have a circuit in my house that blows light bulbs far more often than any >other. I can't determine any reason for this - the voltage seems normal and >there aren't any transient-producers on that same circuit (that I'm aware >of). Long life and rural-duty bulbs make little or no difference. > >Instead of figuring out the root cause, I'm considering resorting to trying >to deal with the symptom (blown bulbs) by putting an NTC in series with the >light fixture somewhere. My thinking is that the mechanism that blows an >incandescent bulb filament is related to the high inrush current into the >cold (and therefore low R) filament, and the physical and thermal stresses >that that inrush causes. > >Any comments on how likely this is to help, and whether or not I can safely >put an NTC in an junction box full of wires? I'd check the NTC's >temperature under load (they get hot) and compare that the the temp. rating >of the wires in the box. I'd also insulate the bare legs of the NTC and try >to make sure it isn't touching anything else. Anyone familiar with the >failure modes of these things? > >Thanks, > >Jim > >-----Original Message- >From: Peter Merguerian [mailto:pmerguer...@itl.co.il] >Sent: Monday, July 10, 2000 7:58 AM >To: emc-p...@majordomo.ieee.org >Subject: Are NTCs Safe to Use in Electrical Equipment > > > >Dear All, > >I have seen some design where NTCs are used to limit inrush currents in >motion controllers. > >Q. Are NTCs safe and reliable as means to limit inrush currents? > >Q. Are there safety considerations to consider for circuits employing NTCs? > >Q. Are there any Approved (previously evaluated) NTC components out there? > > >I appreciate all of your comments and/or links regarding the use of NTCs in >electrical equipment. > >Thanks > >Peter Merguerian >Managing Director >Product Testing Division >I.T.L. (Product Testing) Ltd. >Hacharoshet 26, POB 211 >Or Yehuda 60251, Israel > >Tel: 972-3-5339022 Fax: 972-3-5339019 >e-mail: pmerguer...@itl.co.il >website: http://www.itl.co.il > > > > > > >--- >This message is from the IEEE EMC Society Product Safety >Technical Committee emc-pstc discussion list. > >To cancel your subscription, send mail to: > majord...@ieee.org >with the single line: > unsubscribe emc-pstc > >For help, send mail to the list administrators: > Jim Bacher: jim_bac...@mail.monarch.com > Michael Garretson:pstc_ad...@garretson.org > >For policy questions, send mail to: > Richard Nute: ri...@ieee.org > > >--- >This message is from the IEEE EMC Society Product Safety >Technical Committee emc-pstc discussion list. > >To cancel your subscription, send mail to: > ma
RE: Are NTCs Safe to Use in Electrical Equipment
On the subject of NTC's, please allow me a slight detour from the compliance world to the real world. I have a circuit in my house that blows light bulbs far more often than any other. I can't determine any reason for this - the voltage seems normal and there aren't any transient-producers on that same circuit (that I'm aware of). Long life and rural-duty bulbs make little or no difference. Instead of figuring out the root cause, I'm considering resorting to trying to deal with the symptom (blown bulbs) by putting an NTC in series with the light fixture somewhere. My thinking is that the mechanism that blows an incandescent bulb filament is related to the high inrush current into the cold (and therefore low R) filament, and the physical and thermal stresses that that inrush causes. Any comments on how likely this is to help, and whether or not I can safely put an NTC in an junction box full of wires? I'd check the NTC's temperature under load (they get hot) and compare that the the temp. rating of the wires in the box. I'd also insulate the bare legs of the NTC and try to make sure it isn't touching anything else. Anyone familiar with the failure modes of these things? Thanks, Jim -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Monday, July 10, 2000 7:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Are NTCs Safe to Use in Electrical Equipment
Raychem (www.raychem.com)is one manufacturer that have PTC's that are UL Recognized. I'm not sure if they have NTC's. We use their PTC's as resettable overload devices (in transformers mainly) in our UL Certified product line (medical). We have never had a problem with UL evaluating the devices with PTC's. We have been using them successfully for 5 years. No experience with NTC's but do know they can be used as a limiter for in-rush currents. List of companies that Mfg NTC's (UL recognized?) Western Electronic Corp 805-482-8002 Sensor Scientific 800-524-1610 (www.sensorsci.com) Ketema 714-630-0081 FYI: Sensor Scientific has a planning guide for NTC's Good Luck! -Original Message- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Monday, July 10, 2000 9:58 AM To: emc-p...@majordomo.ieee.org Subject: Are NTCs Safe to Use in Electrical Equipment Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
Are NTCs Safe to Use in Electrical Equipment
Dear All, I have seen some design where NTCs are used to limit inrush currents in motion controllers. Q. Are NTCs safe and reliable as means to limit inrush currents? Q. Are there safety considerations to consider for circuits employing NTCs? Q. Are there any Approved (previously evaluated) NTC components out there? I appreciate all of your comments and/or links regarding the use of NTCs in electrical equipment. Thanks Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
