Frequently asked questions
1. When talking about single to three-phase conversion: what is the difference between a VSD and a converter?
Both VSD’s and converters convert a lower single phase voltage into a higher three- phase voltage. Usually 230V to 3x 400V.
VSD accelerates motors slowly; converters accelerate them fast. VSDs can run motors only at variable speed, converters run machines or even welders.
2. I have heard of static and rotary converters. Which types do you offer?
Static converters have the limitation that only 70% of the machine power is available.
Rotary converters usually offer slow motor starts, relatively weak accelerations and unbalanced phase voltages.
Our Booster TM converters are based on rotary converters, but facilitate fast motor starts (Model E), or the combination of both fast starts as well as balanced voltages under all conditions (model T).
3. Why do I need fast motor starts?
Some machines have to accelerate heavy masses: chucks in lathes, cutter blocks in planers and thicknessers, larger blades in saws.
Deep submersible pumps also have to accelerate a large mass of water on top of them when starting.
Example: When a VSD would accelerate such a mass in five seconds, a rotary converter would do this in two seconds and a Booster TM would do this in half a second.
4. When do I need balanced phases?
Utility supplied three phase voltages are more or less well balanced. Differences between phase voltages are small in industrial areas and could be larger in developing countries. Three phase motors, to a degree, are made to cope with unbalanced voltages. But electronic loads such as power supplies, variable speed drives or CNC machines for example need balanced phases. Acceptable tolerances are published in user manuals, on nameplates.
5. Do converters need maintenance and how long will they last?
Conventional static or rotary converter may have a start contactor. This will fail after some years and need repair or preventative maintenance. Other conventional converter types start without contractors, but they are known for especially weak motor accelerations.
Our BoostersTM are totally maintenance free, with a life expectation of about 80 000 hours or about 25 years. Booster TM converters have solid state switches. No contact will wear, they will outlast anything. Capacitor in a Booster™ are softly switched in and out during zero crossing transitions and do not experience any stress as in a contact operated converter. The internal motor generator has two ball bearings, greased for life.
6. Are inverters more reliable than converters?
Converters may fail after about 25 years or so, for reasons explained above. Inverters have their weak spots: electrolytic capacitors. They still fail after some years or operation. The life expectancy has a direct relationship with the operating temperature. They last longer when properly cooled. Nevertheless, the reliability of our Boosters TM is still about five times higher than that of inverters.
7. I have a 3 phase motor, single phase power only and want a converter - which one do I need?
Most customers do not just have a motor, they have a motor (or several motors) as a part of a machine. If you really have just a motor, i.e. a fan or a pump, it is possible to use either a single to three-phase Variable Speed Drive (VSD) or a single to three-phase converter. But if your motor is part of a machine, it most likely has some kind of a control function - a contactor, a relays or electronic controls. To run such a machine on single phase, you will need a converter. A VSD cannot cope with a control circuitry.
Converters can handle machines with all kind of controls and, depending on the converter type, all kind of electronic loads such as CNC machines or machines with VSDs.
8. Are there any controls on a Booster™ converter?
Converters sometimes have indicators to show if they are still performing well. Ours always work, therefore no need to indicate anything.
9. How do I connect a Booster™ to power and to my machine?
An electrician will install a wall switch, a cable to the house distribution box and a motor rated circuit breaker (see installation instructions). The output can be connected to existing three phase wall sockets or to a distribution box or board with several three-phase sockets for many machines.
10. One of your competitors has warned us about power electronics being sensitive and prone to failures. True?
Silicon Controlled Rectifiers (SCRs) are used to trains, in electric buses and in our converters. They are immune to all external power conditions such as fast transients and over and under voltages. SCR’s in our products are totally protected and failsafe.
11. When should I use an inverter to produce three phase power from single phase?
Only when you have to operate a motor only and only if this motor can be directly connected to the inverter’s output. In all other cases a Booster TM converter is recommended.
When using such an inverter you can set the acceleration and deceleration time as well as the motor’s speed.
12. How do EuroTech inverters work?
A standard inverter or Variable Speed Drive (VSD) has three stages: Rectifier – Capacitor – Inverter. The rectifier produces DC (direct current), the capacitor acts as storage for DC and the inverter chops the DC back into AC (alternating current). Acceleration, motor speed and deceleration are adjustable. A typical inverter in a 50 Hz network would require and produce 3x 400V three phase. If the supply voltage is only 230V, a Eurotech adapter steps up to a higher DC voltage to produce 3x400v AC. This way any 3x400V inverter will run on a standard 230 v supply.
13. My single phase outlets allow for 10A only. Your converter require 20A or more, how do I deal with these discrepancies?
Single phase sockets and switches for industrial applications are available for high currents. Your electrician will install them for you.
14. Can I overload a Booster™?
Boosters™ made for 50Hz always contain a transformer which, when overloaded for a longer period of time, may overheat.
This is different with 60Hz Boosters™ made in USA or Canada: If input and output voltage is the same, no transformer is used inside a Booster™. These converters can be overloaded in curtain cases. A 5hp converter with an input of 240V and an output of 3x 240V normally needs a fuse or protective circuit breaker for 20 Amps. If this circuit breaker is replaced by a 60 Amp one you may run motors and machines up to 15hp.
Find background information about possible overload conditions on page Booster™ Info 3, see the pdf downloads there.
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15.My supply voltage in the UK varies between 220V and 245V. Can this cause a problem?
Europe a while ago set standards: 400V between lines and 230V line to earth.
Some countries increased their official voltages slightly:
Australia for example calls it 415V and 240V.
New Zealand still calls it 400V and 230V but delivers between 230V and 245V to households.
Running motors don't care much:
Their shaft speed is determined by the line frequency plus a small margin called slip.
Their shaft torque is mainly determined by the demand of the machine they are built in.
Because the power demand is stable, their supply current goes down with increasing voltages and vice versa.
To my knowledge, Motors are build for 360V to 440V. They even resist unbalanced voltages found in some developing countries.
Heaters and lamps:
They will draw higher currents with higher voltages. Such loads are rare and voltage variations are probably not large enough to cause failures.
Electronic loads:
The power output should be independent of the supply voltage (within limits).
As with motors, a lower supply voltage will cause a higher current draw and vice versa.
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16.Is there any load a Booster™ cannot be connected to?
Other manufacturers go into very long explanations as to what types of equipment their converters are suitable to operate.
Answer:
The only load a Booster™ of any kind should not be used for is a three phase heating system.
Because the heaters use 230V elements connected to Neutral (in the 50Hz world).
The three phases of a Booster™ rotate around a imaginary point which is not Neutral.
Advise for electricians: combine the three heater phases and connect them to the single phase supply.
This has always worked and saved money because a customer could use a smaller converter just for the motor(s). Typical application: plastic extruders.
If this is not possible: disconnect the heater center point from Neutral and make it floating.
