1
\$\begingroup\$

I’m rewiring a Desktop CNC controller and came across the attached info on one of the internal modules (variable frequency drive).

The two 220v mains power inputs are labelled R / S / E where I was expecting L / N / E or similar for live (active), neutral, and earth.

What does R / S stand for and is this a standard notation that I haven’t seen before, or something else (perhaps a translation issue)?

VFD schematic

\$\endgroup\$
1
  • \$\begingroup\$ Links to the actual documentation would be helpful. \$\endgroup\$ Apr 15 '18 at 18:47
2
\$\begingroup\$

"R,S,T" are arbitrary sequential identifiers with no direct meaning (as opposed to "E" meaning "Earth," for example.)

They correspond to 3-phase power inputs:

  • R = L1
  • S = L2
  • T = L3

Additional info and color conventions can be found in this wiki.

Edit per request:

enter image description here

\$\endgroup\$
2
  • \$\begingroup\$ If you could copy and paste that color info to this answer you may get some up votes. Takes a while to find it. Do a screen shot and crop it. \$\endgroup\$
    – user105652
    Apr 15 '18 at 22:48
  • \$\begingroup\$ @Sparky256 There ya go. Just did a quick copy/paste and adjusted the formatting a bit. Hope it's helpful. \$\endgroup\$
    – Phil C
    Apr 15 '18 at 23:19
0
\$\begingroup\$

The documentation clearly shows 2 phase and 3 phase inputs being R,S and R,S,T but clearly different model numbers.

...so I'd say the controller is probably using US 120/240V consumer supply (and here using 240V as R,S) split phase.
Note here that the two active wires are not 120deg separation but are 180deg separation. So it is NOT 2 phases of a 3 phase supply.

The first diagram shows the input as single 220V input, so this should work using either split phase (240V) in the US or as UK/Aus/etc style 230/240V single phase line if you have an E100S.
It should work for 120/208V 3 phase only if you have an E100T.

\$\endgroup\$
-1
\$\begingroup\$

When you are using only single phase AC, connect the line and neutral to R and S, in either order.

R, S, and T are referring to three phase AC input. There is no neutral or ground. All three lines are "hot", just 120° out of phase with each other.

\$\endgroup\$
3
  • \$\begingroup\$ Are you saying that the OP should use just two phases (R, S) of a three-phase supply? Does that mean that a single-phase supply would be unsuitable? \$\endgroup\$ Apr 15 '18 at 18:47
  • \$\begingroup\$ @AndrewMorton. Any two wires of a 3-phase source is considered single phase. The voltage depends on if the source was 3-phase or split-phase or L-N. Only the voltage between R and S counts. \$\endgroup\$
    – user105652
    Apr 15 '18 at 18:56
  • \$\begingroup\$ @Sparky256 I think I have found the documentation at www.automationtechnologiesinc.com/wp-content/uploads/downloads/2017/02/NOWFOREVER-MANUAL-E-100.pdf which says the S in E100S means single-phase, so the (R, S) would be left over from the (R, S, T) of the E100T three-phase series. ICBW. \$\endgroup\$ Apr 15 '18 at 18:58

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.