Terms And Definitions - WEG CFW-11 Series User Manual

General Instructions

2.2 TERMS AND DEFINITIONS

Normal Duty Cycle (ND): the duty cycle that defines the steady state current value I
110 % during 1 minute. It is selected by programming P0298 (Application) = 0 (Normal Duty - ND). It must
be used for driving motors that are not subject in that application to high torques with respect to their rated
torque, when operating at constant speed, during start, acceleration or deceleration.
I : inverter rated current for use with normal duty cycle (ND = Normal Duty).
nom-ND
Overload: 1.1 x I
Heavy Duty Cycle (HD): the duty cycle that defines the steady state current value I
2
150 % during 1 minute. It is selected by programming P0298 (Application) = 1 (Heavy Duty - HD). It must be
used for driving motors that are subject in that application to high torques with respect to their rated torque,
when operating at constant speed, during start, acceleration or deceleration.
I : inverter rated current for use with heavy duty cycle (HD = Heavy Duty).
nom-HD
Overload: 1.5 x I
Rectifier: the input circuit of the inverters that converts the input AC voltage into DC; it is made of thyristors
and power diodes.
Pre-charge Circuit: it charges the DC link capacitors with a limited current, thus avoiding higher current peaks
when powering the inverter.
DC Link: inverter intermediate circuit; DC voltage obtained from the rectification of the AC input voltage or
from an external power supply. It feeds the inverter output IGBTs bridge.
U, V, W Arms: set of two IGBTs forming the inverter output phases U, V, and W.
IGBT: Insulated Gate Bipolar Transistor; it is the output inverter bridge basic component, working as an electronic
switch either in the saturated (closed switch) or in the cut off mode (open switch).
Braking IGBT: works as a switch to activate the braking resistors; it is controlled by the DC bus voltage level.
Gate Driver: circuit used to turn-on and turn-off the IGBTs.
PWM: Pulse Width Modulation; a pulsed voltage that feeds the motor.
Switching Frequency: it is the inverter bridge IGBTs commutation frequency, normally specified in kHz. Also
known as carrier frequency.
Heatsink: It is a metal part designed for dissipating the heat generated by the power semiconductors.
PE: Protective Earth.
MOV: Metal Oxide Varistor.
RFI Filter: Radio-Frequency Interference Filter; a filter that avoids interference in the radiofrequency range.
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/ 1 minute.
nom-ND
/ 1 minute.
nom-HD
and an overload of
nom-ND
and an overload of
nom-HD