The right choice should not be based only on the power in kW. It is necessary to check the power supply, the rated motor current, the operating mode and the installation conditions.

1. Check the supply voltage

First, determine what power supply the installation has and what voltage the motor requires. The product range offers various configurations, including models with a single-phase 220 V input power supply and models for three-phase 380 V networks.

The input and output voltage of the converter must be compatible with the motor and the electrical grid. It should not be assumed that every inverter can work with every motor.

2. Compare the rated current

The motor power is an important starting point, but its rated current is one of the main selection indicators. The permissible output current of the frequency converter must correspond to the motor current and the intended operating mode.

For applications with heavy starting, frequent accelerations, stops or variable loads, additional technical evaluation is required. Selecting a model based solely on the same kW rating may not be sufficient.

3. Determine the management method

Before purchasing, specify how the start, stop, and speed change commands will be given. Control can be done from a built-in panel, external buttons, a potentiometer, a programmable controller, or an automation system — depending on the capabilities of the specific model.

If remote control is required, check whether an additional operator panel, communication cable or other accessories are required.

4. Adapt the application

• Pumps and fans: speed regulation allows the flow rate to be adapted to actual consumption.
• Conveyors: provides smooth acceleration and adjustment of operating speed.
• Compressors and production machines: the selection must take into account the load and the required starting torque.
• Automated systems: necessary inputs, outputs, and communication capabilities are checked.

5. Provide for proper installation and adjustment

The frequency converter must be installed under the conditions specified by the manufacturer, with the necessary cooling space and appropriate electrical protection. Incorrect parameters may lead to unstable operation or unwanted shutdown of the system.

The settings must be consistent with the data on the motor nameplate — rated voltage, current, frequency, speed, and other parameters required by the specific converter.

Summary

For the right choice, check:

• input and output voltage;
• the rated current and power of the motor;
• the nature of the load;
• the required management method;
• installation and cooling conditions;
• the necessary panels, cables and accessories.

Explore the available E.NEXT frequency converters and compare the technical characteristics of the models.

Important: the selection, connection and adjustment of the frequency converter must be carried out by a qualified specialist in accordance with the motor, the installation and the manufacturer's instructions.

The correct selection of a contactor should not be based solely on the rated current. It is necessary to take into account the type of load, the category of use, the voltage of the control coil, the number of power poles and the required auxiliary contacts.

1. Determine the type of cargo

The first step is to determine what equipment the contactor will control. Electric motors, heating loads, and lighting systems have different starting and operating characteristics.

Motors, for example, can generate significant starting current. Therefore, a contactor suitable for a resistive load is not necessarily suitable for controlling a motor with the same rated current.

2. Check the operating current and power

The rated operating current of the contactor must be in accordance with the current of the controlled load and the applicable utilization category. When controlling an electric motor, the data on the motor nameplate and the technical documentation of the contactor must be checked.

The power in kW can serve as a guideline, but the final choice must take into account the operating voltage, rated current, operating mode and switching frequency.

3. Choose the correct coil voltage

The control coil operates the contactor. Its rated voltage must match the voltage in the control circuit.

Contactors are available with a variety of coil voltages, including AC and DC options. An incorrectly selected coil may prevent normal operation or cause damage to the device.

4. Determine the number of poles

The number of main poles is selected according to the electrical diagram and the load being controlled. For three-phase electric motors, three power poles are commonly used, while other applications may require a different configuration.

Before purchasing, it should be checked whether the specific contactor meets the wiring diagram and installation requirements.

5. Check the auxiliary contacts

Auxiliary contacts are used for signaling, latching, interlocking, and interaction with other control devices. They can be normally open — NO, or normally closed — NC.

Check that the selected contactor has the required configuration. If necessary, additional auxiliary contact blocks can be used if the specific series allows it.

6. The contactor does not replace the protection

The contactor is a control device and does not replace a circuit breaker, fuse or overload protection. When controlling an electric motor, it is usually necessary to provide appropriate short-circuit and overload protection.

Protective and control devices must be coordinated according to the load characteristics and the requirements of the electrical installation.

7. Standard or modular contactor

Standard contactors are widely used to control motors and industrial equipment. Modular contactors are designed for installation in distribution boards and are often used in lighting, heating and other building applications.

The choice between the two types depends on the load, operating mode, required switching capacity, installation location and switchboard design.

Summary

Before choosing a contactor, check:

• the type and rated current of the load;
• operating voltage and power;
• the category of use;
• the voltage and type of the control coil;
• the number of power poles;
• the necessary NO and NC auxiliary contacts;
• installation conditions and operating mode;
• the necessary protection against short circuit and overload.

Explore the available E.NEXT contactors and compare the characteristics of individual series and models.

Important: the selection, connection and adjustment of the contactor and protective devices must be carried out by a qualified specialist according to the load, the electrical diagram and the manufacturer's instructions.

To make the right choice, you must know the purpose of the individual devices, the characteristics of the electrical installation, and the loads that will be powered.

1. Circuit breaker – overload and short circuit protection

A circuit breaker, also known as an MCB, protects electrical circuits and wires from overload and short circuits. It shuts off the power when the current exceeds the permissible values for the circuit.

When selecting, the rated current, number of poles, tripping characteristics, breaking capacity and conductor cross-section are checked. A higher rated current does not automatically mean better protection.

The circuit breaker must be compatible with the permissible current load of the conductors and the characteristics of the load.

2. Residual current protection – leakage current protection

Residual current protection, also known as a residual current device or RCCB, monitors the difference between the currents in the active conductors. If a leakage current above a set value is detected, the device disconnects the power supply.

The main characteristics when choosing are the rated current, the rated differential current, the type of protection and the number of poles.

It is important to know that the standard RCCB does not provide protection against overload and short circuit on its own. Therefore, it must be properly coordinated with appropriate overcurrent protection.

3. Residual current circuit breaker – two functions in one device

A residual current device, referred to as an RCBO, combines the functions of a circuit breaker and a residual current device. It protects the corresponding circuit against overload, short circuit and leakage current.

RCBO allows individual electrical circuits to receive their own combined protection. When selecting, the rated current, tripping characteristic, residual current, type, number of poles and breaking capacity are again checked.

4. Impulse surge protection

A surge protection device, referred to as an SPD, has a different function. It is used to limit short-term surges that can occur due to atmospheric effects or switching processes in the electrical network.

An SPD does not replace a circuit breaker, residual current device or RCBO. Its selection and coordination depend on the electrical installation, the earthing system, the level of protection and the location of the device.

5. How to combine protective devices

Several types of protection can be used in one electrical panel because they react to different dangerous conditions:

• the circuit breaker protects against overload and short circuit;
• the residual current protection reacts to leakage current;
• An RCBO combines overcurrent and leakage current protection;
• SPD limits impulse surges.

The specific scheme depends on the number of circuits, the characteristics of the loads, the type of power supply network and the requirements for the installation.

6. What should we check before choosing?

• is the installation single-phase or three-phase;
• what loads will be powered;
• what is the cross-section of the wires;
• what nominal current is permissible for the respective circuit;
• is leakage current protection necessary;
• is surge protection necessary?
• what are the requirements for selectivity and coordination;
• what free modules are there in the electrical panel.

Summary

There is no single device that can replace all other types of electrical protection. The right solution usually involves a coordinated combination of devices, selected according to the specific installation and its consumers.

Browse the categories with circuit breakers , RCCB residual current devices and RCBO E.NEXT residual current devices .

Important: the design, selection, installation and inspection of protective devices must be carried out by a qualified electrician according to the characteristics of the installation and the current requirements.

For the right choice, it is not enough to know only the thread designation. You must also check the outer diameter of the cable, the size and type of the mounting hole, the material of the gland and the conditions under which it will be used.

1. Measure the outer diameter of the cable

The main indicator when choosing is the outer diameter of the cable, not just the cross-section of its conductors. Cables with the same cross-section can have different outer diameters depending on the number of cores, insulation and construction.

Each cable gland has a specific tightening range. The outer diameter of the cable must fall within this range. If the cable is too thin or too thick, proper fixation and sealing cannot be relied on.

2. Check the size and type of thread

The thread determines how the fitting is mounted to the panel or equipment. Metric and PG threads are often used, but they have different sizes and should not be considered interchangeable.

Before ordering, check the thread designation, mounting hole diameter and wall thickness. If there is no ready-made threaded hole, a suitable lock nut may be required.

3. Choose the right material

Plastic cable glands are widely used in electrical panels, junction boxes and various standard applications. They are lightweight and practical to install.

Brass fittings are typically chosen for higher mechanical requirements, industrial equipment, and applications where metal construction is more appropriate. The specific selection should be based on the environment, housing material, and equipment requirements.

4. Check the required level of protection

The IP rating indicates the level of protection against the ingress of solid particles and water under the conditions specified for the product. It is necessary to check the manufacturer's stated degree of protection for the specific fitting.

The ultimate protection of all equipment depends not only on the gland, but also on its proper installation, the appropriate cable diameter, the seal, the mounting hole and the housing.

5. Consider the working conditions

Before choosing, the conditions at the installation site must be assessed:

• indoor or outdoor installation;
• presence of dust, moisture or water splashes;
• operating temperature;
• vibrations and mechanical stress;
• contact with oils or chemicals;
• need for the material to be environmentally sustainable.

The permissible temperature and resistance to various impacts should be checked in the technical information for the specific model.

6. Check the installation method

To achieve reliable fixation, the cable must be correctly routed through the gland and the sealing element must be tightened according to the design of the product.

Overtightening may damage the gland, seal, or cable sheath. Undertightening may cause the cable to shift and lose the necessary seal.

7. Most common mistakes when choosing

• selection only by the cross-section of the wires;
• neglecting the outer diameter of the cable;
• mixing metric and PG threads;
• incorrect mounting hole size;
• using a fitting outside its tightening range;
• neglect of the material and working conditions;
• acceptance that the indicated IP protection is achieved regardless of the installation.

Summary

Before ordering a cable gland, check:

• the outer diameter of the cable;
• the tightening range of the fitting;
• the type and size of the thread;
• the diameter of the mounting hole;
• the material of the fitting;
• the required degree of protection;
• temperature and operating conditions;
• the need for a locknut or other accessories.

Explore available E.NEXT cable glands , including plastic cable glands and brass cable glands .

Important: the specific gland must be selected according to the dimensions of the cable and opening, the technical characteristics of the product and the operating conditions.

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