Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. Eng8492

    Where do I start for UL listing a PCB

    The easiest way to get a quote from UL. First they will tell you what UL specifications are applicable. In general, you can expect them to demand and test for flame-proof-ness, many different kinds of insulation, demonstrate the ability of your enclosure to prevent access to hazardous...
  2. Eng8492

    EN/UL/CSA 61010-1 (3rd edition) Safety and use of Software to Prevent Electrical or Fire Hazard

    At UL training for 61010-1, the trainer stated that software could not be used to prevent an electrical or shock hazard unless the software was designed and documented to certain other safety standards. For example, such software could not be relied upon to sense that a door was open and turn...
  3. Eng8492

    What are the pitfalls of Designing a piece of Equipment which purposely unbalances a 3 phase circuit

    Yes we will have to augment the current rating on the name plate for all 3 phases even though only 2 phases may be affected.
  4. Eng8492

    What are the pitfalls of Designing a piece of Equipment which purposely unbalances a 3 phase circuit

    Thanks for all the advice. I have done some reasearch that introducing the equipment on a pre-existing 3 phase circuit may cause the following pitfalls: = pre-existing motor loads on that 3 phase circuit to overheat, - cause nuisance tripping of 3 phase protection circuits - nuisance tripping...
  5. Eng8492

    What are the pitfalls of Designing a piece of Equipment which purposely unbalances a 3 phase circuit

    What do you define as large amounts of power? In this case, one of legs will hamust supply 120% of the current that would have flowed in that leg if the equipment had been designed with a balanced 3 phase loads and a seperate 120V circuit. What is the magic number for unbalanced systems that...
  6. Eng8492

    What are the pitfalls of Designing a piece of Equipment which purposely unbalances a 3 phase circuit

    I am designing a piece of machinery for factory production of electronic parts. I have always been taught that it is "bad" to have unbalanced 3 phase loads, but my supervisor has suggested that I steal power frr the 120V circuits off one of the phases of the 3 phase input. My supervisor is not...
  7. Eng8492

    Recommend Parallel EPROM and Programmer Please

    Good suggestion, but there are some analog outputs that need to be buffered and filtered. We found that Atmel makes parallel output eeproms which implement the truth table. We just need to find a generic programmer to put some data into it--have to do that tonight.
  8. Eng8492

    Recommend Parallel EPROM and Programmer Please

    ??? Dont need to a buy a chip to do a layout??? Anyway, we get our parts overnight from Digikey if we call by 4pm...I dont understand your question
  9. Eng8492

    Recommend Parallel EPROM and Programmer Please

    I got tasked to build a suitcase demo for our marketing guys. Absolutely has to go to layout tomorrow evening. There is no time for a micro. -I have 4 discrete inputs which must be mapped to 5 digital outputs...this is not high speed at all..the inputs come from analog comparators. -The outputs...
  10. Eng8492

    Absolute Noob Emergency Stop Controller Question

    Thanks for your interest Lionel. The total load is 3A to guarantee pull in. Im looking for a din rail transorb to prevent arcing. But I am going to use the controller because it implements e-switch contact monitoring, voltage monitoring, and manual restart with a minimum of wiring.
  11. Eng8492

    Absolute Noob Emergency Stop Controller Question

    I think that is an alternate solution if the voltage through the Estop buttons is within the rating of the switch AND is non-hazardous. But now, instead of picking out an Estop controller, I have to check out those two factors and search for undervoltage breaker. Then paint the breaker handle...
  12. Eng8492

    Absolute Noob Emergency Stop Controller Question

    I am using an emergency stop controller. When the emergency stop control is triggered, the output from the control should open a 2 pole contactor carrying split-phase 240VAC and a 3 pole contactor carrying 3ph power. Because I cannot find an e-stop control with any pilot duty ratings (ie UL508...
  13. Eng8492

    Disconnect Switches with 5 ungrounded conductors- Separate Disconnects?

    Thanks for the info Dave. We'll consider using a sticker. I found another solution while I was away--- alot of companies make linkages that can join two 2pole or 3pole switches. 5p and 5p switches exist but are rare.
  14. Eng8492

    Disconnect Switches with 5 ungrounded conductors- Separate Disconnects?

    No step down transformer. There is 240VAC going into our machinery for one thing and 3 phase 380-480VAC for something else. They are provided from the infrastructure so 5 ungrounded conductors go into the machinery.
  15. Eng8492

    Disconnect Switches with 5 ungrounded conductors- Separate Disconnects?

    We have a piece of equipment with 480V 3phase (no neutral) and 240 L1/L2 running into it for a total of 5 wires. Isn't there some rule that you have to break all 5 ungrounded conductors with one disconnection switch, instead of having one switch for the 240V and another switch for the 480V...
  16. Eng8492

    Safety Compliance for Electronic/Electrical Industrial Equipment in Singapore

    Well if you go back up a few threads you can see we are doing a bit more than you are advising. Nonetheless, if you cannot count on your certified test lab for expertise and the stakes are high, its best to find another that will give a written opinion like we did. Really, what would you think...
  17. Eng8492

    Safety Compliance for Electronic/Electrical Industrial Equipment in Singapore

    http://www.emcrules.com/2012/03/fcc-updates-answer-for-exempt.html should be the correct link
  18. Eng8492

    Safety Compliance for Electronic/Electrical Industrial Equipment in Singapore

    Sure, Part 15 is easy is read (just like any EN-61000-* document (lol)) , but the section detailing exemptions can offer an unlimited amount of ambiguity. If you think they are straightfoward, then you may never have faced an ambiguous situation. Part 15 is just an excerpt from CFR, which are...
  19. Eng8492

    Safety Compliance for Electronic/Electrical Industrial Equipment in Singapore

    Thanks for the info guys. Here is my problem. Our NRTL wants to sell us on IEC-61010-1. He put it right in the quote. However, as far as I know, there is no Singaporean law that requires IEC-61010-1. THe NRTL guy wont tell us whether or not this is required in Singapore. In fact, the NRTL guy...
  20. Eng8492

    UL Rating vs NEMA Rating for Motors

    Thanks all for the great information. Never realized that motors would should be a little different than relays tranformers switches etc until I couldn't find any "240 VAC" motors. Great info, thanks. I dont understand the point about choosing a listed motor. My understanding is that UR...

Part and Inventory Search

Back
Top