WEG CFW-11 User Manual - page 13
General Instructions
2
2-2 | CFW-11
2.2 TERMS AND DEFINITIONS
Normal Duty Cycle (ND): inverter duty cycle that defines the maximum continuous operation current (I
nom-ND
)
and the overload current (110 % for 1 minute). The ND cycle is selected by setting P0298 (Application) = 0
(Normal Duty (ND)). This duty cycle shall be used for the operation of motors that are not subjected to high
torque loads (with respect to the motor rated torque) during its operation, starting, acceleration or deceleration.
I
nom-ND
: inverter rated current for use with the normal duty (ND) cycle.
Overload: 1.1 x I
nom-ND
/ 1 minute.
Heavy Duty Cycle (HD): inverter duty cycle that defines the maximum continuous operation current (I
nom-ND
)
and the overload current (150 % for 1 minute). The HD cycle is selected by setting P0298 (Application) = 1
(Heavy Duty (HD)). This duty cycle shall be used for the operation of motors that are subjected to high torque
(with respect to the motor rated torque) during its operation, starting, acceleration, or deceleration.
I
nom-ND
: inverter rated current for use with the heavy duty (HD) cycle.
Overload: 1.5 x I
nom-ND
/ 1 minute.
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: charges the DC Link capacitors with limited current, which avoids higher peak currents
at the inverter power-up.
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 of the inverter output phases U, V, and W.
IGBT: insulated Gate Bipolar Transistor; basic component of the output inverter bridge. The IGBT works as an
electronic switch in the saturated (closed switch) and cut-off (open switch) modes.
Braking IGBT: works as a switch to activate the braking resistors; it is controlled by the DC Link voltage level.
Gate Driver: circuit used to turn-on and turn-off the IGBTs.
PWM: pulse width modulation; pulsed voltage that feeds the motor.
Switching Frequency: frequency of the IGBTs switching in the inverter bridge, normally expressed in kHz.
Heatsink: it is a metal part designed for dissipating the heat generated by the power semiconductors.
PE: protective earth.
MOV: metal oxide varistor.
PTC: resistor which resistance value in ohms increases proportionally to the temperature increase; used as a
temperature sensor in electrical motors.
NTC: resistor which resistance value in ohms decreases proportionally to the temperature increase; used as a
temperature sensor in power modules.