SINGLE TO THREE PHASE CONVERSION WITH ELECTRONIC MOTOR SPEED CONTROL

NOTE - IT IS NOT POSSIBLE TO VARY THE SPEED OF A SINGLE PHASE MOTOR
OR A DUAL-SPEED THREE PHASE MOTOR

GENERAL - Most small single speed three phase motors are wound for operation from either a 380/415-volt or a 220/240 volt three phase supply. The speed of an induction motor is directly related to its supply frequency. A 650-frequency converter offers the facility to electronically vary the speed of the motor by varying the frequency of the motor. For small machine tool applications this facility should be used in conjunction with rather than as a direct replacement for an existing mechanical variation of speed. Note that a 650-frequency converter can only operate machinery driven by 200/240 volt DELTA connected three phase motors if the electricity supply parameter is 220/240-volt single phase.

FEATURES of the 650 frequency converter (IP20 enclosure only)

Conversion of a mains 220/240 volt single phase supply to a mains 200/240 volt three phase supply
Electronic variation of speed from 0 to twice nominal rpm of motors (zero Hz to 100Hz).
Higher frequencies attainable within reason.
IP20 enclosure as standard
Six output sizes - 250W (0.33hp), 370W (0.5hp), 550W (0.75hp),
750W (1hp), 1100W (1.5hp) and 1500W (2hp)
Digital display of output frequency.
Controlled acceleration and deceleration of motor
Motor protection against overload, undervoltage and overvoltage.
Fixed speed settings if required.
Removable operator control module accessed by extension cable (extra).
Facility for external potentiometer control of motor speed via control pendant (extra).
CE Marked and EMC compliant
RFI filter fitted as standard
12 month manufacturer's warranty as standard
Made in England

IMPORTANT - The output from the 650-frequency converter offers all necessary motor protection and control. The frequency converter should be connected directly to the motor terminals. The customer should ensure that any inherent safety devices incorporated into the machine (e.g. emergency stop, limit switches, guard switches) and/or manual switching mechanisms (e.g. lever control) are wired to interrupt the input supply to the frequency converter.

650 Frequency Converter in IP54 Enclosure
For "hostile" working environments such as woodturning,
Power Capacitors offer the 650 technology in a sheet steel single door enclosure to IP54.
The enclosure measures 400 mm (high) x 200mm (wide) x 200mm (deep)
and can be wall mounted.
Start/Stop/Forward/Reverse and Potentiometer Control of Motor Speed as standard.
Cable glands for supply and motor cable fitted as standard.
Screened cable available at extra cost.

What is the difference between a 650-frequency converter and a TRANSWAVE converter?
1. A frequency converter offers the motor a three-phase supply at 220/240 volt. The TRANSWAVE offers the motor a supply at 380/415 volt, establishing an artificial third phase at 380/415 volt via an interaction with the motor.
2. A frequency converter varies the frequency to the motor offering a means by which the motor speed can be varied infinitely. The TRANSWAVE is a fixed frequency system. Variation in motor speed can only be achieved by mechanical means.

When should I consider the use of a 650-frequency converter?
1. For single motor applications where electronic variable speed is required independently of or in conjunction with a mechanical variation of speed.
2. For applications where frequent stop/start or forward/reverse is required (e.g. screw-cutting, tapping).

When should I consider the use of a TRANSWAVE converter?
1. For applications where the motor cannot be connected for operation from a 200/240 volt three phase supply (e.g. multi-speed motors).
2. For multi-motor applications.
3. For motor sizes in excess of 1.5kW.

Do I have to modify my machine to accommodate a 650-frequency converter?
1. All motor connections must be changed from 380/415 volt (STAR) to 220/240 volt (DELTA).
2. The motor must be connected directly to the frequency converter output, bypassing the traditional means of starting/stopping/protecting the motor.
3. Be wary of ancillary motors such as coolants and table feeds. These are likely to have to be disconnected completely and fed from an alternative source.

When a motor is connected to a frequency 650 converter, does it lose torque/power?
1. There is a direct relationship between the torque of a motor and the frequency at which it operates. This is why it is recommended to pre-set the 650 between 25Hz (half-nominal speed) and 75Hz (one and half times nominal speed). At these frequencies the level of torque available is acceptable.
2. At particularly low frequencies it may be necessary to consider the implications of secondary motor cooling since the fan built into the motor could lose its ability to cool the motor effectively. The pre-sets outlined above have been chosen to eliminate this requirement.