converting single to 3 phase

[jason straw]

hello everyone,
i am replacing a single phase motor with a 3 phase motor on my bandsaw.. the relay switch box is/ was for 3 phase originally... I have a magnetic on and off switch and a kill switch at the foot brake.. i am not sure of a few things...
I know that line comes in on t1, t2, t3, and at the bottom of it all the load plugs in there..
i am switching out the heaters to the appropriate size...
one of the wires to my on off switch is wired to t3 line currently and another wire from the on/0ff switch goes to the t3 (load? )on the lower part of the contacts (the one with springs.. i have attached a photo...
if anyone has any leads, links, suggestions i would appreciate it.
let me know if better phots would hl..
thanks

[Mike Henderson]

Just a question. Since you're putting in a 3-phase motor, you are planning to use a three phase supply, aren't you? If you are, you'd keep the three phase control box.

Mike

[Chip Lindley]

Hi Jason! The "L" is for LINE. 3-phase input usually comes in on L1, L2, L3. Output power leaves the overload block to the motor at T1, T2, T3.

I do not see a 4th latching relay on your contactor. Three sets of contacts will be needed for the three 3-phase lines. A 4th will be needed for a momentary-type pushbutton station. For single phase input, only two contacts were needed; the third was used as the latching relay.

Changing to 3-phase, your only choice for controling the coil with this contactor would be a click-on / click-off switch which cancels out the safety factor of not restarting after a power interruption. The starter will, however, shut down if over-amperage trips an overload heater.

Below is a schematic of a typical Square D 3-phase starter which uses line voltage to control the coil. Study the path of the wiring and see how your contactor, overload block and pushbutton compares. Regardless of make, most magnetic motor starters are basically the same.

SqD 3ph Starter Schematic.jpg