So my Kress died (can't complain, it has served me very well), and I decided to upgrade to a 1.5kW Chinese spindle. So far it's been a lot of work to install it, and I still haven't decided where to place the vdf, so I do hope the new spindle will be every bit as amazing as it's reputed to be.
And now I found out I need CY cable between the vfd and the spindle, so I have some re-wiring to do (through cable tracks, oh!)
My question is which would be the correct core thickness of that CY cable for my use: 0.75mm, 1mm, 1.5mm?
I would use 0.75mm or 1mm CY 4 core 0.75mm will be fine..Clive
The Following User Says Thank You to Clive S For This Useful Post:
Thanks! I've ordered the 0.75mm because I it'll be a bit thinner and I assume nicer to handle.
Here is a chart showing what each size is rated at:
Here is a list showing the watts to amps conversions:
WATTS TO AMPS CONVERSION
60 Watts = 0.26 Amp
100 Watts = 0.43 Amp
200 Watts = 0.87 Amp
300 Watts = 1.30 Amp
400 Watts = 1.74 Amp
500 Watts = 2.17 Amp
600 Watts = 2.61 Amp
700 Watts = 3.04 Amp
800 Watts = 3.48 Amp
900 Watts = 3.91 Amp
1000 Watts = 4.35 Amp
1100 Watts = 4.78 Amp
1200 Watts = 5.22 Amp
1300 Watts = 5.65 Amp
1400 Watts = 6.09 Amp
1500 Watts = 6.52 Amp
1600 Watts = 6.96 Amp
1700 Watts = 7.39 Amp
1800 Watts = 7.83 Amp
1900 Watts = 8.26 Amp
2000 Watts = 8.70 Amp
2100 Watts = 9.13 Amp
2200 Watts = 9.57 Amp
2300 Watts = 10.00 Amp
2400 Watts = 10.43 Amp
2500 Watts = 10.87 Amp
2600 Watts = 11.30 Amp
2700 Watts = 11.74 Amp
2800 Watts = 12.17Amp
2900 Watts = 12.61 Amp
3000 Watts = 13.04 Amp
3100 Watts = 13.48 Amp
3200 Watts = 13.91 Amp
3300 Watts = 14.35 Amp
3400 Watts = 14.78 Amp
3500 Watts = 15.22Amp
Last edited by Lee Roberts; 26-05-2016 at 08:26 AM..Me
Lee that is helpful but the chart does not show if the cables are in free space or bunched together in one sleeve as the cable will have to be derated when bunched because of heat build up.
Edit Lee the Watts to Amps conversion has to state the voltage I know you have it done at 230V
Last edited by Clive S; 26-05-2016 at 08:40 AM...Clive
Cg represents the derating factor for grouping cables.
A cable with a current rating of 6 amp installed in trunking alongside other circuits, that's circuits not cables!, would now have a Cg value, the Cg value is 0.57.
This means the cable current rating becomes: 6 x 0.57, that's 3.42 amp.
To add to this, you should note that the grouping factors are based on assumption, the assumption that all of the cables in the group are carrying their rated current.
So, if however a cable is not going to be carrying more than 30% of its grouped current rating, that cable can actually be omitted from the group rating calculation...
...an example, if you've got lets say 6 circuits in a group of cables but 1 of those cables is known to be operating below the said 30% consistently, you can safely calculate the group on the basis that it only consists of 5 circuits.
Here are some correction factors for multicore cable:
OK Clive, how did I do?
Last edited by Lee Roberts; 26-05-2016 at 09:50 AM..Me
The Following User Says Thank You to Lee Roberts For This Useful Post:
26-05-2016 #9OK Clive, how did I do?..Clive
Lee, what works is not the same as what is safe and what is recommended.
That is a more realistic and better data, even if you step down one size, 1.5mm2 is what should be used. 0.75mm2 is for small desk lamps, not for motors. Then again, I know most people never really use their spindles at maximum load, so it is never really going to be a problem and in many cases even 0.5mm2 might be OK, but I think 1.5mm2 is the minimum if you want to play it safe. My 1.5kW is rated 8A and I am pretty convinced that saving on cable costs is not a good decision. Also, if you ever decide to use a vector controlled spindle you will notice that it pulls more current as well, so what is the point of under dimensioning the cable?
Last edited by A_Camera; 26-05-2016 at 12:28 PM.
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