ABB ACS 502 Series Installation & Start-up Manual

Contents

ABB ACS 502 Series Installation & Start-up Manual Manual pdf 20 page image

Chapter 2 – Overview of the ACS 502/5042-6ACS 502 Installation & Start-up ManualGeneral InformationAbout Your ACS 502/504Functional DescriptionPower-on sequence When line voltage is switched on, the capacitor bank is charged first via thecharging circuit. The charging takes less than one second. During this time,the thyristors on the rectifier bridge are not conducting.GENERAL WARNING! The maximum permissible number of chargings inone minute is four. If the DC bus is charged more often, the charging resistormay fail due to excess heat. Therefore, it is recommended that you do not usethe input power switching on and off as a Start/Stop command.The power supply of the ACS 504 comes from the capacitor bank. The powersupply turns on when the voltage on the capacitors has reached about300 VDC. Subsequently, the Control Interface Card, Motor Control Card andMain Circuit Interface Card are energized.When the DC-voltage has reached 80% of its nominal value, themicroprocessor on the Motor Control Card energizes the Input ProtectionCard. The thyristors are gated fully conducting and the thyristor-dioderectifier behaves like a normal 6-pulse diode bridge.The cooling fan turns on at initial power-on. To prolong the useful life of thefan bearings, the fan is automatically turned off after one minute, unless:• The drive has a RUN command, or• Heatsink temperature is above 113°F (45°C).Control In normal duty the drive follows commands and references either from thekeypad or the terminal block on the Control Interface Card. The control signalsource selection and the way the drive interprets these signals are configuredby parameters.Power section Power flow through the drive in normal duty is from AC-input line throughthe rectifier bridge to the DC-filter capacitors which sustain a constant DC-voltage. The nominal value for this voltage is 1.35 x VIN.The Inverter consists of six power semiconductor switches whose operation iscontrolled by the Motor Control Card via the Main Circuit Interface Card.Turning these switches on and off in a certain sequence is called modulation.The modulation frequency in the ACS 504 is about 3 kHz at maximum andcannot be altered.The potential at any terminal U2, V 2, W 2 (T 1, T 2, T 3) of the inverter can onlybe high or low. The modulation determines which one. At any instant, the lineto line output voltage is either 0 V when the switches in these phases are in thesame position or ± 1.35 x V IN when the corresponding switches are indifferent positions.