Modern production processes use more and more advanced automation systems, operating at an increasing speed. Inverters are commonly used to control three-phase motors working in these systems. That is why it is so important to choose an inverter that will meet the requirements of the specific application.
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Inverter selection criteria
When choosing an inverter, you must answer five basic questions:
What will the inverter be used for?
The basic issue is to match the load characteristics to the inverter characteristics. It should be selected in such a way that the output power of the inverter satisfies, and even exceeds, the motor demand for power necessary at start-up and during stable operation of DC or AC. Check engine parameters such as:
- supply voltage, engine power and current
- connection type
- and turnover
How to choose the inverter according to the parameters of the power source?
The next step is to determine the available input voltage, frequency and power. Also check that there is enough space in the control cabinet for the inverter with the necessary accessories.
How to choose the inverter for the process?
When choosing an inverter, you should think about two important issues:
Feedback: Specify the expectations for the specific application here. Due to the large internal memory, fast processors and output input systems, many inverters now work as process controllers, not speed controllers. They can count pulses, determine how to stop the engine, or send an error signal. Remember, however, that regardless of the type of process and the measured signals, inverters are used to control the motor.
Communication: in some cases, a simple display is sufficient, in others - messages sent via analog or digital outputs. On the other hand, when it is necessary to collect large amounts of data, e.g. for statistical purposes, communication via fieldbus or industrial Ethernet is a good solution.
How to choose the inverter housing?
A suitable housing extends the inverter life and provides adequate protection.
Many inverters are part of large systems and operate in clean, air-conditioned control rooms - such devices require enclosures with a minimum degree of protection.
However, most inverters operate on site, under very variable conditions. For this reason, choosing the right housing is the key to their long-term work. According to UL / NEMA classification:
- Class 1 enclosure is designed to work in a clean, dry environment, at temperatures between 0 - 40 ° C, and altitude up to 1000 m above sea level.
- Class 12 enclosure - for operation in humid and polluted surroundings, i.e. standard conditions prevailing in most production plants.
- Class 4 enclosure - for work in wet and very polluted environment.
How to choose the inverter manufacturer?
One of the most important issues from the point of view of the installation and operation of inverters is the technical support provided by the manufacturer. Good access to the technical support may be necessary for the production line to operate, which means shorter downtimes and less losses. Therefore, when choosing a manufacturer, it is best to choose a local, authorized manufacturer's supplier and stay away from anyone who does not have a qualified service center.
You should also pay attention to the product warranty. Guarantees for a period of 18 months to two years are commonly used. However, some manufacturers offer guarantees that last five years and longer.
