There is just no way to predict the environment in which an AC drive will be mounted. Some of the hardest installations can be found in industrial settings.
Drives must be built from the bottom up with a variety of uses in mind, as well as the ability to function from a local control panel, fieldbus, or discrete input/output (I/O) while dealing with various climatic conditions, power sources, motor types, and distances. If the environment is not taken into account from the start, it may lead to greater service costs, higher maintenance expenses, a decline in operational reliability, or, worst of all, more downtime.
Here, we assume that the drive is sized for proper control of the motor and application (voltage, power, response time, and I/O needs), and it includes additional best practices for the drive and application to operate without issue in the environment where it is installed.
Think about the following:
Mechanical: Does the setting where the drive is mounted require an enclosure?
Input power: What kind of and how reliable a power supply is it?
The motor’s wiring provides power
I/O: the application’s control wiring has been installed and routed. Fieldbus wiring for tamper-free control and monitoring.
There are several factors to consider while choosing AC drives. Whether the product runs for a few seconds, several hours, or continuously for a year, it must be able to drive the motor without stopping.
In an ideal world, an engineer could create the application from the ground up while taking into account all of the required components, but this is frequently not the case. Every day, new installations, retrofits, and upgrades are made to existing facilities. The information that follows enables the best chance for trouble-free functioning.
Spacing
The AFD can be properly cooled since there is room around it for air to circulate. The manufacturer offers suggestions for above-ground, below-ground, and side space. Drives can occasionally be installed side by side with no room around them.Ammonia, chlorine, and other aggressive gasses can harm the electrical and mechanical parts of an AFD. Polychlorinated biphenyl door seals and track deterioration can be caused by contaminated cooling air. A clear sign of an aggressive atmosphere is corroded copper. In aggressive atmospheres, enclosures and conformal-coated circuit boards are recommended.
Power supply for distribution network, voltage, and line disruptions caused by input power
The power supply (230, 460, or 600 volts) must be understood before choosing an AC drive. Only single-phase power is accessible in some distant regions, necessitating a unique design. This information is easily accessible in new designs.
The following are important things to look into:
Voltage level: decide whether to use a single-phase or three-phase drive for that voltage:
Transformer configuration: does the transformer have a properly grounded secondary? If not, the drive might require its metal oxide
Varistors or filter covers taken off: Are there any problems with the power quality? This can call for the employment of an isolation transformer, an external reactor, or a drive with an integrated direct-current choke or line reactor.
When wiring cables for input power, size wiring based on the AFD’s input current and comply with local and national electrical codes. Because these cables carry high voltage, they should be kept away from control wiring, other power wires and motor wiring to avoid inducing voltages in other cables.
Grounding and shielding for motor wiring
It’s important to inspect the wire used to connect the drive and the motor. Consider that the motor wiring in the past might have been made up of individual conductors in a conduit when replacing a starter or contactor with the drive during a retrofit. To operate a motor and change speed, AC drives use insulated-gate bipolar transistors at the drive output. The cable needs to be properly sized and created for the installation site. The proper drive and motor combination is required, in addition to the cable. To choose the right cable and determine whether a specific conduit is required, take into account whether the environment contains moisture, oil, or the possibility of the cable being crushed.
A cable made for AC drives is the best kind to use. The ground and shield conductors that the motor needs will be provided by this cable. When switching at output terminals at higher frequencies, grounding and shielding are essential. Grounding is done for safety purposes and uses single-point grounding to create a path from the motor back to the drive. This indicates that the ground conductor is linked to both the ground terminal on the drive and the motor. By using a single point of grounding, it is possible to prevent the high-frequency noise from spreading to other pieces of machinery. An output reactor and a dU/dT filter are advised when installing a drive on an older motor in order to safeguard it from peak voltages that may happen at the motor terminals as a result of reflected waves.
Elevated voltage
Even with the equipment switched off and locked out, induced voltage from output motor wires running together can charge equipment capacitors. Failure to employ insulated cables, metal conduits, or separate output motor cables could result in fatalities or severe injuries.
Remember to:
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- Adhere to local and federal electrical code requirements for cable sizes.
- Run output motor cables separately or use shielded cables or metal tubes
- Observe the wiring guidelines provided by the motor manufacturer.
Control wiring
Fieldbus, STO, digital and analogue I/O, and encoder – Integrity of the control wire is essential. Shielded cables and a separation from the wiring for the power and motors are needed for the control wiring for digital and analogue signals, fieldbus cables, safety circuits, and feedback devices. If the power or motor wire needs to cross, do it at a 90-degree angle.
Pick wiring that is rated for the voltage, signal, and current it will carry. To prevent crosstalk, use the shield. It’s common to forget about the cord from a mounted, remote control panel. Additionally, the cable needs to be run away from the motor and power connections.
Highest standards
The finest installation guidance and chance for trouble-free operation are found in manufacturer recommendations and manual instructions. Use the checklist below to go over each installation location if a deviation arises. Due to cost or how and where they are installed, some regions could not apply or can be altered. Recommendations from the manufacturer should be as closely followed as possible, and local and federal wiring and installation regulations should be followed.
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