Mouser components to high voltage resistive divider - Page 1
Forum section: electronics / projects

author: edmundopt
author_rank: Regular Contributor
timestamp: February 05, 2014, 04:29:15 pm
content: HelloMy friend asked me if I can improve an industrial heater. The machine only has ON/OFF and a visual indicator that is up to temp after heating up.Anyway, the idea is to add visual information about the ammount of power into the heater resistors, if is full on (like starting) or just maintaining (holding temperature), this will allow the machine to make cycles without turning off.I take a look at the PSU, it is a three phase full wave rectifier, the exit of the PSU and control system is marked as 480volts DC.So, I want to measure that, I think a resistive voltage divider of 100:1 will allow me safely to have a reading on multimeter. I expect some form of pulse width modulation on the heater resistors.So, the closest I can to place the divider is about 15cm away from the PSU connectors, it will require some hook-up wire, 1kv wire will ensure no arcing ? maybe higher ?I have access to this :1kv awg22 high temp high voltage wire:http://pt.mouser.com/ProductDetail/Belden-Wire-Cable/83025-002100/?qs=sGAEpiMZZMtW9UaYX5J1tA98TbJZaPGw9O%2frHi%252bqczw%3dfor the resistive voltage divider , I was thinking of this:5 units of2MOHM 500mW resistorshttp://pt.mouser.com/ProductDetail/IRC-TT-electronics/MH37-2M-1TR/?qs=sGAEpiMZZMu61qfTUdNhG9gR7%2fu94EVJTEI036ohYQI%3d1 unit of100Kohm 500mW resistorshttp://pt.mouser.com/ProductDetail/IRC-TT-electronics/MH37-100K-5TRLF/?qs=sGAEpiMZZMu61qfTUdNhGz34irntT%2fJFkeSjL7OynMc%3dI need to insulate the 2MOHM resistors, any sugestions ?If you can provide link to mouser, it would be great!I have watched eevblog #85 video, do I need those high voltage capacitors ?Any sugestions to other wire or resistors value are welcome!

author: Monkeh
author_rank: Super Contributor
timestamp: February 05, 2014, 05:43:11 pm
content: I'd advise just getting a multimeter safe to read 480VDC with. They're pretty easy to find.

author: edmundopt
author_rank: Regular Contributor
timestamp: February 05, 2014, 05:59:53 pm
content: I have agilent U1273A, it's 1000VDC, but I am not going to connect it directly to the PSU outputs, its high current!I really need the safer voltage divider

author: ejeffrey
author_rank: Super Contributor
timestamp: February 05, 2014, 06:10:23 pm
content: That agilent is perfectly safe to connect to the PSU. Its internal voltage divider has the appropriate clearance distances to be safe and it is well contained in case of a surge that exceeds the 1000V rating.

author: edmundopt
author_rank: Regular Contributor
timestamp: February 05, 2014, 06:19:07 pm
content: Maybe some more clarifying is required.The power supply exit are two 12mm bolts, then one metal plate to close the psu, and another metal plate with some heating protection enclosures the control system, I can not turn it on without bolth of the covers.So I need two wires, 15cm each to connect to the bolts, then connect to a resistive divider inside the second pannel, and then get the wires with low voltage out of the enclosure.I think this is the safeste way! Can you provide me some help building the custom probe ?