3 phase changeover switch

[leeko]

Hi all,

I'd like to use a changeover switch to switch the output from a vfd between three identical 3 phase motors. I understand all the warnings about switches or disconnects on the load side of a vfd, but the switch will be in a locked cabinet in a single user environment, so I'd like to proceed.

I bought one of these:
http://www.amazon.com/gp/aw/d/B00GW...e?ref_=pe_385040_30332190_TE_3p_M3T1_ST1_dp_1

Unfortunately, it came without a wiring diagram or any English instructions. The store told me they don't have any English instructions available.

The switch has 12 terminals, but none are indicated as "input". I took a multimeter to the switch in the zero position, and found 3 terminals on one side with no continuity with any of the other terminals. Good so far. But, when I switch to any of the other positions, at least one of those "input" terminals will show continuity with more than one other set of terminals. I'm a bit confused as to why - I understood that switching only 1 or 2 of the three phases is not desirable. Or, is this switch not the correct type for this application?

Thanks in advance for any advice ,

Lee

 

[nehog]

o=open or off
x=closed or on
term=terminal (which are numbered)
So below, if the switch is in the left position connected terminals are 1:2, 5:6, and 9:10.

Switch Position
Term___1___0___2___Term
1______X___O___O___2
3______O___O___X___4
5______X___O___O___6
7______O___O___X___8
9______X___O___O___10
11_____O___O___X___12
Term___1___0___2___Term

(So in position 1, terminal 1 connects to terminal 2, terminal 5 connects to terminal 6, and terminal 9 connects to terminal 10. In Position 2, terminal 3 connects to terminal 4, terminal 7 connects to terminal 8 and terminal 11 connects to terminal 12. Bet that is not what you wanted, was it? )

 

[Rookie2]

I used to install these on generators (only about 5x as many contacts), a local commercial generator shop may help.

 

[leeko]

I'm not sure that's right, because my switch has 4 positions: 0, 1a, 1b and 1c. Terminals 4, 8 and 12 are in line on one corner of the housing, and have no continuity with the other terminals in one switch position (nominally zero, because the front plate can be swivelled). When I move the switch clockwise, terminal 4 had continuity with terminal 1 AND terminal 3, but no continuity with terminal 2 (all of those terminals ate at the same "level" around the switch housing. Terminal 8 had continuity with no other terminals in this switch position. Terminal 12 has no continuity with the other terminals either.

I'm sure it's me not understanding how this switch's terminals are laid out, but I can't for the life of me figure it out!

Lee

 

[leeko]

If I click the switch clockwise to the next setting, 4 has no continuity, 8 has continuity with 5 and 7, and 12 has no continuity.

Click clockwise 1 more time: 12 has continuity with 9 and 11, 4 and 8 no.

Confused!