Brother A-7200b-405

[Union Level Leather]

Hi Y’all

i just bought a Brother A-7200B-405 sewing machine, it says on the control box single phase 220-240. I’m having a problem with the cord configuration, it has a green, blue, black and brown                                                                                                                                 wires. I’m not sure what kind of plug to use. Do they make a 4 wire plug?  

I have a NEMA 6-20P plug, it’s right configuration for the outlet I have but only has 3 studs in it.

 

thanks in advance ;

George 

 

                                   

[R8R]

6-20p plugs are generally used for 110v applications where you want to plug it into a dedicated 20 amp circuit, not a 15 amp which is standard household current.

Single phase 220v plugs are typically larger dryer plugs, etc. You will need a dedicated 220v circuit receptacle and a dedicated plug for it. 

 

Now, if it has blue, brown or orange it might actually be wired for 3 phase input. I would get an electrician to look at it for you.

 

[480volt]

Rating plate should tell you what you need to know. Since it says single-phase, first thing I would do is verify if all the conductors in the cord are actually in use. If it really is single-phase 220-240, it should only need two hots and a ground. Ground is always green, everything else is arbitrary.

[Uwe]

The control box circuitry usually runs on single phase 220V.  It's the motors that are often true 3-phase affairs. There may be a separate type plate on the motor. A four conductor power cord hints very strongly at 3-phase power.

Alas, you may be able to run the whole affair on single phase power.

On my 3-Phase Durkopp Adler 467 Efka setup all three power wires connect to the motor, but only two of the three power wires continue on to the controller box to supply single phase power. On other machines it is less obvious what's going on.

A three phase motor will continue to run just fine with only two power wires connected once it starts rotating (but with a lower horsepower rating.)

I just bought a rotary phase converter from a guy who said had it connected to his three-phase Adler 467 sewing machine (same as mine.) One day he forgot to turn on the rotary phase converter before he turned on the machine, and, lo and behold, everything worked just fine without the rotary phase converter turned on. He was lucky in that he had (by chance) the power wires connected just right  - the two original incoming single phase power wires have to be the ones that continue on to the controller (you have a one in three chance of getting it right by accident.) 

The "proper" way to connect three phase equipment to single phase power supply is to use a rotary phase converter. They normally consist of a control box and a special 3-phase generator motor. A two HP rotary phase converter should be fine to run a single sewing machine. They cost about $250-$400. 

In any case, make sure you are comfortable doing electrical work or get some somebody who is.

Edited November 26, 2017 by Uwe

[Union Level Leather]

Thanks everyone, I appreciate your input.

George

[480volt]

Uwe has forgotten more about sewing machines than I’ll ever know, and using an RPC is sound advice, that’s how I would do it. I work with three phase equipment frequently and motors from fractional HP up to about 50 HP. Three phase motors will continue to run if they lose one phase (single-phasing) at reduced HP and torque, but they cannot start themselves on single phase. They just sit there and hum and draw excessive current until you shut it off or it burns up. You can get one to start on single phase if you get it spinning before you apply voltage, but it will happily run in either direction. If the motor rating plate does indicate three phase, and you buy an RPC to feed it, be aware that it can be made to run either direction  depending on how you connect it and you likely won’t know what that direction is until you bump it. If it’s wrong, reversing direction just requires swapping any two phase conductors feeding the motor. Good luck, don’t let the smoke out.

[SARK9]

I've used both the RPC and the electronic *static phase converters*  and I would have to say, the static version is probably the way to go for indoor (such as IN HOME) use. Once connected, they are invisible to the process....like they are not even there. You do take a small HP hit with either the rotary or static, and the roto is said to be slightly better in that regard, but really, for sewing machines, its probably academic. The roto phase type requires a 220v single phase motor to run constantly if you are needing 220v/3ph power....so you have a couple of the primary disadvantages of using a clutch motor right there....the motor is always running, meaning noise and power consumption, in addition to your always-on old school sewing machine motor. The upside is, the roto is rated in terms of the motor HP it will START...it will *run* several motors simultaneously as long as the start load is not exceeded. An electronic servo motor or a VFD are probably similar in cost, but it won't give you the high production automatic functions like programmable back tack/thread trim/needle up/down etc. if those things are required.

 

-DC

[Union Level Leather]

Thank you all for your input.

After further investigation of 4 wires on the cord, going into the control box the black wire was a dead end, so that left me with 2 hots and a ground, after I connected the plug, off she went, great machine powerful and will sew anything I put under the foot including firm leather. Thread trimmer, thread wiper, auto back tack, programmable etc etc.

I was worried it was 3 phase even though it said single phase on the control box! It had a 3 phase sticker above the box?

 

The NEMA 6-20P plug worked well.