Single to 3 phase

[hareng]

After a long winded affair i bought an M300 last October and powered it up for the first time this morning.

After no help what so ever from Direct Drives only to try and get me to fork out an additional £550 over current digital 5.5hp inverter £650.
I took the liberty of buying a 5.5hp rotary Transwave convertor last week. Motor used to create a phantom 3rd phase and is very noisy.

This will interest such people and heres my findings armed with an electric power consumption meter in real time.

Teco MA7200 digital 5hp powered up on standby uses 11p/hr.
Teco MA7200 just about tripping the contactors in the lathe spindle with 3hp (2.2Kw) motor an astonishing 68p/hr under no load.

Transwave 5.5hp rotary convertor powered up uses 13p/hr.
Transwave powering the lathe spindle with 3hp motor 31p/hr no load.

For comparison a 1hp single phase 240V motor on mill spindle uses 13p/hr.
Likewise an old English single phase lathe with 1 1/2hp motor uses 21p/hr no load.

This is the opposite of what i was expecting, the digital having serious losses in the conversion. One thing in the digitals favour is whilst spindle isnt running its using 11p.hr but when it is uses more than double that of the rotary.

 

[madkayaker]

have just finished fitting a 7.5kw one for a customer to run a load of woodworking kit they are noisy!

 

[hareng]

My rotary is a lot noisier than the actual lathe running, not far off the compressor.

 

[madkayaker]

this one is drowned out by the band saw but when powering the lathe it is noisy.

 

[graffian]

My rotary is a lot noisier than the actual lathe running, not far off the compressor.

Only just got it running!

Is the idler mounted inside the case?
I mounted my idler on the floor;-) It's sitting on lump of 2" thick plasterzoate and isn't to noisy. if it touches anything the noise increases. I am sure the motor has got louder since I have had it[that was 2003].

 

[Shox Dr]

Interesting findings there Hareng.

It's a bit late now, but what speed motor are you using I was told that the slower speed 3ph motors do make a lot of noise when used as a RPC.

 

[hareng]

No idea just bought it as is, case is mounted off the motor and weighs 75Kg.
Like the one on the right http://www.powercapacitors.co.uk/Power_Capacitors_Site/Converter_Downloads.html

Even mounting on rubber, foam etc, it only reduces around 10db.

My concern is the digital inverters are marketed as efficient, my findings reveal they are twice as expensive to run.

Some of you may eligeable for a free electric consumption monitor from your service provider.
If anyone has one i would like some confirmation of their findings.

 

[Luke]

My concern is the digital inverters are marketed as efficient, my findings reveal they are twice as expensive to run.

In general, they are, compared to running a motor continuously. However, they'll never be more than 100% efficient, typically they're about 95% at full load. Power losses are predominantly fixed, rather than relative, so you'll see a lower 'efficiency' when in standby, or with low loads.

Have you got a line reactor fitted? If you haven't, I wouldn't be surprised if the drive is upsetting your energy meter.

Luke

 

[madkayaker]

i put the clamp meter on the one i installed and found that with all the kit on (don't know the exact KW as most of the motors would have been an **** to get at) it was drawing 27A on the supply and 11A per phase. but each phase doesn't have a true voltage to earth reading so lost interest in trying to work out the effecincy. We do find at work that the "high" effecincy motors draw more current than the ones that have been there since 1966 but they are spining faster

 

[hareng]

Luke no line reactor or anything.

DAB radio works normal from AC thats a good sign and must be little RF.
Used the digi for a few hours this morning, current draw does go up when putting a cut on. Yet to use in anger.

Digital wont start the spindle 50/50 chance when geared for 2500rpm, even when it does must take around 30 secs. Suggests to me its not quite man enough but will soon tell when i put a serious cut on within optimum speed range for the job.

 

[ronan]

This is interesting hareng, as i have a colchester lathe i need to power from single phase , you reckon the inverter is not the way to go ? I was told by anyone i asked that they are the way to go in powering three phase machinery from single phase.

 

[madkayaker]

for those that might be interested i emailed transwave about running 400V single and three phase welders off there units. this was the PDF that i got back

TRANSWAVE Sales
T – 0121 708 4522 – F – 0121 765 4054
E - transwave@powercapacitors.co.uk
www.powercapacitors.co.uk
APPLICATION NOTES - WELDING EQUIPMENT
Both three-phase and two-phase 415-volt welding sets can be operated from a single-phase supply in
conjunction with a TRANSWAVE rotary converter. As welding load is resistive, not inductive, it is necessary to
use a rotary converter to develop the voltage in the “artificial” third phase, independently of the welder. The
converter should be of sufficient capacity to maintain the voltage on the artificial phase when the welder is
operated at its maximum current rating.
Some converter sizes need to be modified for welding purposes. When necessary, the modification
incorporates a hand/auto switch, which bypasses the automatic boost circuit. Two-phase welding sets can also
be operated from dedicated transformers. A guide to the recommended sizes of rotary converter and
transformer is given in the table below. Note that any rotary converter used for welding purposes can still be
used for standard motor applications.
WELDING
CURRENT
3-PHASE INPUT
CURRENT (APPROX.)
CONVERTER
REFERENCE
160A 8A per phase RT-4.0KW (standard)
200A 10A per phase RT-7.5KW (standard)
250A 12A per phase RT-7.5KW (standard)
300A 15A per phase RT-7.5KW (standard)
350A 17A per phase RT-15KW (standard)
400A 20A per phase RT-15KW (standard)
WELDING
CURRENT
2-PHASE INPUT
CURRENT (approx.)
CONVERTER
REFERENCE
160A 12A per phase RT-7.5KW (standard)
200A 15A per phase RT-7.5KW (standard)
250A 18A per phase RT-15KW (standard)
300A 24A per phase RT-15KW (standard)
350A 27A per phase RT-15KW (standard)
WELDING
CURRENT
2-PHASE INPUT
CURRENT (approx.)
TRANSFORMER
REFERENCE
160A 15A per phase 8550/240V – S7
200A 18A per phase 8550/240V – S7
250A 23A per phase 8550/240V – S7
300A 27A per phase 13979/240V – S7
350A 30A per phase 13979/240V – S7
400A 36A per phase 13979/240V – S7
USE OF HAND/AUTO SWITCH MODIFICATION
For motor applications - Switch should be in “Auto” position. Converter operates as per standard operating and
installation instructions.
For welding applications - With hand/auto switch in “Auto” position, start converter as normal. Once motor on
converter has started, switch hand/auto switch to “Hand”. The Welder can now be operated.
POWE R C A PA C I TOR S L IMI T E D
3 0 R E D F ER N ROA D
T Y S E L E Y
B I RMINGHAM
B 1 1 2 BH
1q
BS EN ISO 9001 Certificate No. 8174