MICROMASTER 420s are a range of frequency inverters for controlling the speed of three phase AC motors. The various models available range from the 120 W single-phase input to the 11 kW three-phase input.
The inverters are microprocessor-controlled and use state-of-the-art Insulated Gate BipoIar Transistor (IGBT) technology. This makes them reliable and versatile. A special pulse-width modulation method with selectable Pulse frequency permits quiet motor operation. Comprehensive protective functions provide excellent inverter and motor protection.
The MICROMASTER 420 with its default factory settings, is ideal for a large range of simple motor control applications. The MICROMASTER 420 can also be used for more advanced motor control applications via its comprehensive parameter lists.
The MICROMASTER 420 can be used in both ‘stand-alone’ applications as well as being integrated into ‘Automation Systems’.
Main Characteristics Easy installation Easy commissioning Rugged EMC design Can be operated on IT line supplies Fast repeatable response time to control signals Comprehensive range of parameters enabling configuration for a wide range of applications Simple cable connection 1 Output relay 1 Analog output (0 – 20 mA) 3 Isolated and switchable NPN/PNP digital inputs 1 Analog input, ADC: 0 – 10 V The analog input can be used as the 4th digital input BICO technology Modular design for extremely flexible configuration High switching frequencies for low-noise motor operation Detailed status information and integrated message functions
Protection characteristics Overvoltage/undervoltage protection Overtemperature protection for the inverter Ground fault protection Short-circuit protection i2t thermal motor protection PTC for motor protection
Performance Characteristics V/f Control ♦ Flux Current Control (FCC) for improved dynamic response and motor control ♦ Multi-point V/f characteristic Automatic restart Flying restart Slip compensation Fast Current Limitation (FCL) for trip-free operation Motor holding brake Built-in DC injection brake Compound braking to improve braking performance Setpoint input via: ♦ Analog input ♦ Communication interface ♦ JOG function ♦ Motorized potentiometer ♦ Fixed frequencies
Ramp function generator ♦ With smoothing ♦ Without smoothing
Closed-loop control with proportional-integral controller function (PI)
WARNING ♦ To ensure the safe operation of the equipment, it must be installed and commissioned by qualified personnel in full compliance with the warnings laid down in these operating instructions. ♦ Take particular note of the general and regional installation and safety regulations regarding work on dangerous voltage installations (e.g. EN 50178), as well as the relevant regulations regarding the correct use of tools and personal protective gear. ♦ The mains input, DC and motor terminals, can carry dangerous voltages even if the inverter is inoperative; wait 5 minutes to allow the unit to discharge after switching off before carrying out any installation work. ♦ The inverters can be mounted adjacent to each other. If they are mounted on top of each other, however, a clearance of 100 mm has to be observed. ♦ IP20 protection is only against direct contact, always use these products within a protective cabinet.
Avoiding Electro-Magnetic Interference (EMI) The inverters are designed to operate in an industrial environment where a high level of EMI can be expected. Usually, good installation practices will ensure safe and trouble-free operation. If you encounter problems, follow the guidelines stated below.
Action to Take Ensure that all equipment in the cubicle is well grounded using short, thick grounding cable connected to a common star point or busbar Make sure that any control equipment (such as a PLC) connected to the inverter is connected to the same ground or star point as the inverter via a short thick link. Connect the return ground from the motors controlled by the inverters directly to the ground connection (PE) on the associated inverter Flat conductors are preferred as they have lower impedance at higher frequencies Terminate the ends of the cable neatly, ensuring that unscreened wires are as short as possible Separate the control cables from the power cables as much as possible, using separate trunking, if necessary at 90º to each other. Whenever possible, use screened leads for the connections to the control circuitry Ensure that the contactors in the cubicle are suppressed, either with R-C suppressors for AC contactors or ‘flywheel’ diodes for DC contactors fitted to the coils. Varistor suppressors are also effective. This is important when the contactors are controlled from the inverter relay Use screened or armored cables for the motor connections and ground the screen at both ends using the cable clamps
Screening Methods Gland Plate The Gland Plate Kit is supplied as an option. It allows easy and efficient connection of the necessary screening. See the Gland Plate Installation Instructions contained on the Docu-CD. Screening without a Gland Plate Should a Gland Plate not be available, then the inverter can be screened using the methodology shown .