Need some help with electrican schematics (hoists and 3 phase induction motors)

Xeno

Hey guys, just need a little help. An electrician drew this schematic for me on how a hoist in a factory works. It looks like a 3 phase induction motor. (I redrew this schematic.)



So I get some stuff, but not the rest. So electricity for L1/L2/L3 goes to the motor in T1/T2/T3. If you want to spin the motor counter clockwise, you open the first 3 switches(?) and close the other 3 to the right, and that reverses L1 and L3, causing the motor to spin the other way, allowing it to go forward and back? All this stuff controlling it is the contactor? Tell me if I have this right so far.

Now, here is where I get confused. Those 2 lines to the side, circle #1. What is that? It seems like it is connected to the parts that control the hoist going up and down. But how? What are those squiggly lines in circle #1? Power goes from L1 and L2 and when the up button is pressed, it completes the circuit and sends power to the up button? Same thing with the down button?

Thanks a lot guys. Confusing stuff.

Jean Claude Van Calm

Looks like circle one is a transformer that supplies power when the up or down switch is closed (pressed) to complete the circuit. Circle 2 is most likely an illuminated "UP" led that lights when the switch is pressed, same for the down circle and its respective switch, the LEDs don't run on 3 phase power which is why the transformer is necessary.


Whoops forgot your first paragraphs of questions. 3 phase stuff is no fun but yes i believe you got it. Most likely one set of the three contacts is the same physical switch as the up button (quad pole quad throw switch.) while the other three are part of the down switch. All they do is supply power in a different direction when their button is pressed labeling switches especially when they have multiple contacts is pretty important.

Edit note: grammar is hard!

Slo

Alright, so circle one is just an isolation transformer, which basically takes the electrical current 'runoff' (flux) and puts it into a seperate circuit, this creates a seperate entity that operates independently. So it's taking the flux off the main power for your hoist, and bleeding off a few volts to create a control circuit, that closes the motor starter in up/down position.

With 3 phase stuff, a motor goes from A, B, C. Any time you swap any of those phases (eg. to B,A,C) you change the direction of the phases, also changing the direction of motion. (Look at b, a, c, its just abc backwards and moved down a bit on the rotation)

So when you press Up, it closes the first set of contacts, and keeps the phases at ABC(or 123), whereas if you press Down it goes to CBA(321).

Any time you have a 3 phase motor, and swap 2 of the leads, you reverse direction.

Sorry if I'm a bit muddled, it's been a weird night.