TECO WESTINGHOUSE VARIABLE FREQUENCY DRIVES

A Variable Frequency Drive (VFD) is a type of controller used to vary the speed of an electric motor. Input to the VFD is a fixed Power supply that the VFD with then use to control the speed and Torque of a given motor. Motor Speed can be varied by changing the frequency of the power supply waveform.

Output Speed is:Speed = 120 * Frequency / Number of motor Poles

VFD Operation

A VFD takes the fixed Input Frequency and Voltage Power supply and converts it to a controlled Output PWM Waveform at a Voltage and Frequency that is determined by the VFD. In so doing the rotational speed of the motor can be controlled by the Speed relationship indicated above.

VFD & MOTOR COMPATIBILITY

Motor and Drive compatibility can be complex. Many variables should be considered when determining the suitability of a particular motor for use with a VFD. 

Extremes in some or all of these factors will add to the severity of the application and can result in premature motor failure:

• Torque requirements (constant or variable)
• Speed Range for control
• Line/System Voltage
• Drive switching (carrier) frequency
• Motor Construction
• Cable Length and type of cable used between VFD and motor
• VFD dv/dt
• Temperature and Humidity
• Grounding System

VFD EFFECTS ON THE MOTOR

When a motor is powered by a PWM waveform the motor windings very often see a large differential voltage, either from phase to phase or turn to turn. When the voltage differential becomes great enough, Ozone is created and there is a corona or partial discharge inside the motor. This energy is corrosive to the varnish on the motor windings. PWM waveforms can also magnify shaft voltages which lead to arcing across the bearing and causing a phenomena called fluting in the bearing race. This can lead to premature bearing failure and needs to have corrective action taken in order to avoid any issues.

TECO E510 COMPACT DRIVE

A compact, low cost, and versatile AC Drive that is easy to program and ideal for OEM’s.

Applications include Mixing, Treadmills, Lathes, Fans, AC Contactor Replacement, Milling, Small Conveyors, Pumps

E510 Drive Features:

• 0.5 to 3 HP (CT), 230V, 50/ 60Hz, 1-Phase
• 0.5 to 40 HP (CT), 460V, 50/ 60Hz, 3-Phase
• 1 to 75 HP (CT), 460V, 50/ 60Hz, 3-Phase
• Parameters Grouped by function
• Built-in PLC Functionality
• PID Process Control Loop
• Built-in Modbus & BACnet Protocols
• 5 Digit Operator’s Keypad with Speed Pot
• Digital and Analog Inputs and Outputs have Extremely Fast (~4 msec) Update Time
• Auto Run Mode (Cyclic Operation)
• Power Loss Ride Through
• Automatic Voltage Regulation (AVR)
• Complies with IEC 60018-2-78, UL, cUL, CE, & RoHS