Rockwell Automation 1302 575v AC Drive - Canada Only - Manual (Page 8)

2–2 1302 AC Drive Description
Publication 1302-5.0 — January, 1998
The 1302 Drive is an AC PWM (pulse–width–modulated) inverter
that operates on single–or three–phase power as detailed in Figures
2.1 and 2.2. AC input power is applied to the Drive’s input
terminals. Voltage transients are suppressed by three
metal-oxide-varistor (MOV) suppressors. These suppressors keep
any input voltage transients within the maximum voltage rating of
the input diode module.
The input diode module rectifies the incoming AC voltage into a
constant DC bus voltage which is filtered by the DC bus capacitor
bank. An internal DC-to-DC power supply uses power from the DC
bus and provides the necessary voltages required by the Drive. Under
regulator software control, the IGBT (insulated-gate
bipolar-transistor) inverter bridge converts the constant DC voltage
into an AC PWM waveform. The regulator switches the IGBT
inverter bridge using a 4, 6, or 8 kHz carrier frequency
(user-selectable). A low carrier frequency maximizes the power
rating of the Drive but also increases acoustic noise. A high carrier
frequency selection reduces acoustic noise but results in a derating of
the Drive’s efficiency.
The volts per hertz (V/Hz) regulator governs the open-loop operation
of the Drive for adjustable speed performance of AC induction and
synchronous motors. The regulator maintains a ratio of voltage to
output frequency that provides constant or variable torque across a
wide speed range. Drive operation can be adjusted by the parameters
entered through the keypad. A microprocessor on the Regulator
board controls Drive regulation. See Figure 2.3. The Regulator
board accepts internal power feedback signals and an external speed
reference signal. The Regulator board provides display data for a
four-character display, which is used to indicate Drive parameters,
parameter values, and fault codes.
The Drive can be controlled either locally through the keyboard and
display (see Chapter 7) or remotely through the terminal strip (see
Chapter 5).
The Drive is intended to operate trip-free under any condition. The
Drive uses selected signals to extend the acceleration (starting) and
deceleration (stopping) rates of the motor when an overcurrent
condition occurs. When a fault does occur, however, the regulator
generates an instantaneous electronic trip (IET) signal to turn the
Drive off (coast-to-rest). The Drive stores an indication or record of
the IET fault, which can be viewed on the four-character display.
After a fault, the STOP/RESET key or a user-supplied IET RESET
pushbutton must be pressed to reset the IET signal and clear the fault
from the Drive.
Drive Description