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emergency-stop-and-aux-13amp-sockets [2016/11/22 19:03]
johnwillis
emergency-stop-and-aux-13amp-sockets [2016/11/22 19:09] (current)
johnwillis
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 ====Materials==== ====Materials====
  
-How rubber 5 core cable 16a 3ph 3m £15+How rubber 5 core cable 5 core 1.5 mm^2 £15 
  
 Tri cable £20 Tri cable £20
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 As discussed this is the parts list and cost for the electrics of the lathe. As discussed this is the parts list and cost for the electrics of the lathe.
 +
 +
  
 ====Suppliers info==== ====Suppliers info====
  
 {{::​chint-nc1-data-sheet.pdf|Chint NC1 contactor info}} {{::​chint-nc1-data-sheet.pdf|Chint NC1 contactor info}}
 +
 +=====Comments=====
 +===David Smith 2/11/16===
 +Also, we might be able to get it cheaper than that.
 +www.electriccable.co.uk ​ charge only £1.19/m + VAT, but then charge
 +£9.50 + VAT for delivery. ​ So, perhaps we can find somewhere that does
 +it for a reasonable price but with cheap delivery. ​ Searching around,
 +CEF sell it by the cut length, and they have a place in Avonmouth, but
 +they don't list a price on their website. ​ It might also be worth asking
 +Edmundson Electrical just up the road from the Hackspace, next to
 +Screwfix. ​ They certainly sell it; it's whether they do it in cut
 +lengths or just whole reels.
 +
 +> We still need to figure out the configuration and exactly which thermal overload to buy.
 +
 +I've been researching into this; this is what I've learned:
 +
 +o Yes, the current value quoted for the thermal overload really is the
 +expected current consumed by the motor. ​ Even the 100 mA ones (although
 +I don't know why you would bother having a 100 mA, three-phase motor...)
 +o For the overload to be truly effective, I think it needs to be one per
 +motor. ​ I have a sneaking suspicion that there is more than one motor in
 +the lathe, although ICBW.
 +o Therefore, we need to confirm both (a) the number of motors in the
 +lathe, and (b) the maximum full load current (also called FLA (full load
 +amperes)) of each motor.
 +o If there'​s more than one motor, we should consider either mounting the
 +box on the lathe rather than the wall, or the thermal overload relays
 +and associated contactor in the electrics box on the end of the lathe
 +rather than in the new control box - otherwise, we'd end up with
 +multiple three-phase cables running from the box on the wall to the
 +lathe, which seems rather excessive.
 +o The thermal overload relay doesn'​t actually switch off the current to
 +the motor. ​ When overloaded, it opens the NC contact, which should then
 +turn off the contactor. ​ Therefore, we need to wire this contact in as
 +another "​emergency stop" button.
 +o In addition, when tripped, the thermal overload relay also closes the
 +NO contact. ​ If we wanted, we could wire this in to, say, a neon
 +indicator on the box to show that the overload had tripped.
 +o Do we want a manual or automatic reset? ​ The Chint ones are all manual
 +override, but other manufacturers also do automatic ones that reset
 +themselves after a minute or so.  If we had a manual trip, it would mean
 +that, whenever it was triggered, it would render the lathe unusable
 +until someone authorised to open the control box could get down to the
 +Hackspace and reset it.  Is that what we want?
 +
 +-- 
  
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