Static phase converters

[martin33100]

Hi, just bought a M300 lathe and soon I will be looking for a phase converter.

I have looked at the static Transwave's and also our local machine mart has there's on offer, when I spoke to there technical guy he said there static converters only have power on 2 phases and gets the other phase from the motor, is that right?, I thought my lathe would need all 3 phases.

Thanks in advance

[naffsharpe (Nathan)]

Nothing wrong with a static converter. I've run my Harrison L5 on a Transwave (no connection) for years. At hobby levels of use and at light production use mine is very good. Protect it with it's own circuit/ breaker/RCD. My lathe has the two speed motor and all gearbox speeds are available. Nathan.

[John Rudd]

Just bear in mind that if you supply it with a dedicated mcb like Nate suggests, you get the mcb with the right curve rating.....I'd suggest a C type rather than the usual B type, else you find it trips unexpectedly on startup....Your local 'trician should be ble to help...

[naffsharpe (Nathan)]

I totally agree with John, I may even suggest that instead of a 30ma RCD, that you go for a 100ma RCD. You'll never notice the difference in protection but your household circuits might. That is, given you are already protected by a 30ma RCD. Nathan.

[martin33100]

Thanks guys, I do mechanical and electrical work in the engineering department at Southampton docks and I work on the cranes and straddle carriers. I posted the question about converters as I have never used one and all the work I do here is all 3 phase supply.
I have a 40A supply going to my new work shop at home and once the lathe goes in I will start the wiring, currently just the lighting circuits are done.
I am puting a 16 and 32A socket for welders so may just use the 32A socket to supply the converter, if they were to trip I would change to a Type C mcb but most boards (unless you by blank) come with type B mcb's.
I was going to do a split load board with the lighting and roller door on one split and all the sockets and machines on the other split, that way any power tools or machines won't take out the lights or door.

[vintageandclassicrepairs]

Hi
With the Transwave You need to make sure that the "real" phases are used for the control circuit
They recommend adding a pilot motor to "improve" the phase voltage balance.

Recently I bought a Harrison 165 that came with a Transwave converter
The lathe motor is 3hp but only suitable for 380/420 volts. Its Delta connected for this voltage so cannot easily be run from the usual 240v inverter setup that I intended to use 
When running on the Transwave the motor did not sound or run smoothly though
Motor bearings are good and it spins smoothly, I played about with capacitors and varying the voltage settings on the converter without much sucess

Long story short I have swopped motors to a 3hp single phase that I had going spare
I am intending to put up a thread up on the various aspects of recommissioning and a few mods on the Harrison when I get it back together

John

[martin33100]

Hi
With the Transwave You need to make sure that the "real" phases are used for the control circuit
They recommend adding a pilot motor to "improve" the phase voltage balance.

Recently I bought a Harrison 165 that came with a Transwave converter
The lathe motor is 3hp but only suitable for 380/420 volts. Its Delta connected for this voltage so cannot easily be run from the usual 240v inverter setup that I intended to use 
When running on the Transwave the motor did not sound or run smoothly though
Motor bearings are good and it spins smoothly, I played about with capacitors and varying the voltage settings on the converter without much sucess

Long story short I have swopped motors to a 3hp single phase that I had going spare
I am intending to put up a thread up on the various aspects of recommissioning and a few mods on the Harrison when I get it back together

John

The guy that sold me the M300 ran it on a Transwave converter but it was the rotary type.

[philf]

.....

The lathe motor is 3hp but only suitable for 380/420 volts. Its Delta connected for this voltage so cannot easily be run from the usual 240v inverter setup that I intended to use......

Are you sure it's Delta connected and not Star? Delta is for 240v!

Phil.

[martin33100]

I had a chat with the guys today that make the Transwave converters, they said a rotary type converter around 5-7hp would atleast future proof my workshop if I get an other 3 phase kit.
Somewhen I do want a larger compressor to keep up with die grinders etc so that may well be 3 phase as well.

[vintageandclassicrepairs]

Hi Phil,
Yes I'm sure of the motors connections, it is different to the "usual" 380/220v dual voltage configuration
The plate on it shows 380-420v only and is Delta connected with each phase connected to two internal winding ends,
Way back when! there was a 550/600 volt system used in Industry, maybe it could have been star connected for the higher voltage 

Martin and All,
With the Transwave static converter the motor is started by applying line voltage across two phase connections and capacitors connected from one phase to the third phase connection
(same principal as a single phase capacitor run motor)
The magnetised  rotor spinning within three 120 degree mechanically spaced windings generates the third phase
That is how a rotary converter works, the pilot motor acts as a generator ( a 2850rpm motor is preferable for this but not essential)

To be honest I was disappointed with the performance of the Transwave that came with my lathe
The phase voltages were very high, getting over 500v depending on the switch setting
The motor buzzed and growled and drew high current on no load
It tested out ok with my motor tester, inductance and resistance wise

I spent almost 30 years working on power generation and associated electrical plant so am fairly confident of my abilities (electric motor wise)  

The PITA situation is that there's a 3 phase transformer on my boundary fence
But the capital and running costs of installing 3phase is unrealistic

John

[jb3cx]

Here's my penny's worth .for the last 20 years I have used a transwave static converter 7.5 kw
I run a bridgeport mill ,Harrison m 250 .there are only 2 problems I have came across .(1) the minimum load is 1.5 kw .(2) if I have the Harrison in high gear ,on startup it labourers up to,top speed
I have been told that I need a bigger feed cable from the house to the workshop .ok I will get round to it sometime .what I have been doing is to start the bridgeport first thus acting as a pilot motor ,and I have not had any problems starting the m250 in high gear .also it's a lot quieter than running a rotary converter .olso the other downside of using a converter of this size is the min loading 1.5 kw i.e. 2hp
Therefore on the other machines I have I use small inverters .
Peter

[martin33100]

Hi Phil,
Yes I'm sure of the motors connections, it is different to the "usual" 380/220v dual voltage configuration
The plate on it shows 380-420v only and is Delta connected with each phase connected to two internal winding ends,
Way back when! there was a 550/600 volt system used in Industry, maybe it could have been star connected for the higher voltage 

Martin and All,
With the Transwave static converter the motor is started by applying line voltage across two phase connections and capacitors connected from one phase to the third phase connection
(same principal as a single phase capacitor run motor)
The magnetised  rotor spinning within three 120 degree mechanically spaced windings generates the third phase
That is how a rotary converter works, the pilot motor acts as a generator ( a 2850rpm motor is preferable for this but not essential)

To be honest I was disappointed with the performance of the Transwave that came with my lathe
The phase voltages were very high, getting over 500v depending on the switch setting
The motor buzzed and growled and drew high current on no load
It tested out ok with my motor tester, inductance and resistance wise

I spent almost 30 years working on power generation and associated electrical plant so am fairly confident of my abilities (electric motor wise)  

The PITA situation is that there's a 3 phase transformer on my boundary fence
But the capital and running costs of installing 3phase is unrealistic

John

I am guessing it was a static converter your lathe came with?.

[vintageandclassicrepairs]

Hi Martin,

I am guessing it was a static converter your lathe came with?.

Yes it is, Rated about 4Kw

For the price of a new Transwave I would prefer to go for an inverter instead
 
I have inverters on the 3hp milling machine and 7.5hp (5.5Kw) Colchester
These run sweet as a nut

I am going with the 3hp single phase motor on the Harrison simply because it was free and the wiring to
it is there from the old lathe that has gone to a new home

John