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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Relay back emf protection
Following on from the Automotive Relay thread;
What are the reasons behind the apparent fact that relays last longest in this order of coil protection: 1. No protection at all 2. Zener diode 3. Resistor (6 x coil resistance) 4. Diode (No protection being the relay lasts longest, the standard diode being the worst thing for the relay - forget the circuit protection issues just now) From this data - scroll to the bottom for a chart: http://www.te.com/commerce/DocumentD...=CS&DocLang=EN Cheers, Gareth. |
#2
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Relay back emf protection
On 10/22/2014 1:52 PM, Gareth Magennis wrote:
Following on from the Automotive Relay thread; What are the reasons behind the apparent fact that relays last longest in this order of coil protection: Arcing on opening. 1. No protection at all Fastest opening. Less damage to contacts. 2. Zener diode If indeed your order is correct, Slow opening. 3. Resistor (6 x coil resistance) Slower Opening. 4. Diode Slowest Opening. Most damage to contacts. (No protection being the relay lasts longest, the standard diode being the worst thing for the relay - forget the circuit protection issues just now) From this data - scroll to the bottom for a chart: http://www.te.com/commerce/DocumentD...=CS&DocLang=EN Cheers, Gareth. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#3
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Relay back emf protection
On 10/22/2014 3:23 PM, amdx wrote:
On 10/22/2014 1:52 PM, Gareth Magennis wrote: Following on from the Automotive Relay thread; What are the reasons behind the apparent fact that relays last longest in this order of coil protection: Arcing on opening. 1. No protection at all Fastest opening. Less damage to contacts. 2. Zener diode If indeed your order is correct, Slow opening. 3. Resistor (6 x coil resistance) Slower Opening. 4. Diode Slowest Opening. Most damage to contacts. http://web.archive.org/web/201101040...fs/13c3264.pdf |
#4
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Relay back emf protection
On 10/23/2014, 12:53 PM, bud-- wrote:
On 10/22/2014 3:23 PM, amdx wrote: On 10/22/2014 1:52 PM, Gareth Magennis wrote: Following on from the Automotive Relay thread; What are the reasons behind the apparent fact that relays last longest in this order of coil protection: Arcing on opening. 1. No protection at all Fastest opening. Less damage to contacts. 2. Zener diode If indeed your order is correct, Slow opening. 3. Resistor (6 x coil resistance) Slower Opening. 4. Diode Slowest Opening. Most damage to contacts. http://web.archive.org/web/201101040...fs/13c3264.pdf This is very interesting, it raises points I had never considered such as the momentary current flow through the diode and coil, and how that can stress other parts. The two articles are good reading! It explains why (in my field of pinball repair) manufacturers stopped putting suppression diodes on the coils and instead put them in place to protect the driver devices (transistors/Mosfets, etc.). Thanks for bringing this topic up! Do note that both articles say you HAVE to protect the driver device from the back EMF!! John :-#)# -- (Please post followups or tech inquiries to the newsgroup) John's Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 (604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
#5
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Relay back emf protection
"bud--" wrote in message eb.com... On 10/22/2014 3:23 PM, amdx wrote: On 10/22/2014 1:52 PM, Gareth Magennis wrote: Following on from the Automotive Relay thread; What are the reasons behind the apparent fact that relays last longest in this order of coil protection: Arcing on opening. 1. No protection at all Fastest opening. Less damage to contacts. 2. Zener diode If indeed your order is correct, Slow opening. 3. Resistor (6 x coil resistance) Slower Opening. 4. Diode Slowest Opening. Most damage to contacts. http://web.archive.org/web/201101040...fs/13c3264.pdf Thanks for that link. Interesting indeed. Gareth. |
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