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Connectors are the invisible backbone of modern industrial equipment – they ensure reliable transmission of power, signals and data. Whether it’s high-performance power connectors, precise signal connections, or highly shielded data connectors, every industrial application has specific material, design, and protection requirements. In this article, we will highlight the different types of connectors, their uses, and what to look for when selecting the right connector.
Connectors are electromechanical components that transmit electrical or optical signals between two components and allow for a detachable connection. They typically consist of two main parts: Plug (male, with pins or contacts) and socket (female, with matching contact receptacles). Connectors thus ensure a reliable, standardized, and easy-to-maintain connection of systems and components and are often used in automation as well as in machine and plant engineering.
To ensure safety, interoperability, and high performance, connectors are subject to a variety of national and international norms and standards. These normative requirements define, among other things, mechanical and electrical properties, test methods, protection classes, and requirements for electromagnetic compatibility (EMC).
A central standard for industrial connectors is DIN EN 61984, which sets general safety and performance requirements for electrical connectors without their own switching function. Among other things, it describes test methods for insulation resistance, current-carrying capacity, and mechanical durability to ensure safe use in industrial environments. ISO/IEC 11801 is of great importance for connectors in networks and IT infrastructures. It defines the requirements for connectors and cable systems for telecommunications and data networks, including categories for transmission speeds and EMC behavior.
Compliance with standards such as DIN EN 61984 or ISO/IEC 11801 ensures that connectors meet technical and safety requirements, provide long-term reliability, and are globally compatible. A supplementary overview of general safety aspects in mechanical engineering can be found in our blog on safety standards in mechanical engineering.
The following overview shows different types of connectors, their properties as well as normative requirements.
| Designation | Description | Example | Signals | Data | Power Observe max. values! |
Applicable standard (Other standards may apply) |
|---|---|---|---|---|---|---|
| Rectangular connectors (see also hybrid connectors) |
Rectangular connectors consist of a housing and a pin insert. Depending on the series, connectors have a defined number of contacts. The modular design allows combining modules for signal, data and power transmission. |
 |
Very suitable | depending on type (often extended via modular data inserts) | high-power versions also available | IEC 61984 |
| Device connectors | According to VDE 0623, connectors with pins for rated voltages in low-voltage networks up to 230V. They plug directly into end devices/loads. |  |
Limited suitability | Limited suitability | Well suited (device power supply e.g. IEC connector) |
IEC 60320 |
| Sensor connectors | Sensor connectors come in many shapes, sizes and types. Mainly designed for signal transmission. Some types can also be optimized for data via better shielding. |  |
Highly suitable | suitable variants available (e.g. M12-D) | Limited suitability (only for low currents) |
IEC 61076-2 |
| CEE connectors | CEE plugs are power connectors. Various plug and socket types differ by color and rated current. Rated voltage is defined by color: Yellow - 110V (100-130V) Blue - 230V (200-250V) Red - 400V (380-480V) Black - 500-690V Type 16A /230 V Type 32A / 400V (3-phase) Type 63A / 400V (3-phase) |
 |
Not suitable | Not suitable | Highly suitable (for high current and voltage) |
IEC 60309 |
| Power connectors (high-current connectors) |
Mainly designed for transmitting large electrical energy. Besides CEE connectors, many other types like circular connectors exist. Some variants may also include signal cores. |
 |
Depending on type | Less suitable | Highly suitable (for high power e.g. motor connections) | IEC 61984 |
| Hybrid connectors | Combine different transmissions, e.g. power supply and data transmission |  |
Highly suitable (depending on type) |
Highly suitable (depending on type) |
Highly suitable (depending on type) |
IEC 61984 |
Industrial connectors can be divided into three main categories depending on the type of transmission. Power connectors, signal connectors, and data connectors.
Each of these categories performs a specific function and differs in electrical characteristics, design, and applications.
Power connectors are designed to transmit electrical power to supply equipment, machines, or drives. They are characterized by their ability to conduct high energy currents and their particularly robust construction. Typical representatives in this category are CEE connectors for industrial power connections, high current connectors for power electronics and electromobility, and M23 connectors for motor drives.
Signal connectors or Signal plugs, on the other hand, are used to transmit analog or digital control and measurement signals. They simplify the connection of sensors, actuators, and control devices in industrial automation systems. Common variants of signal connectors include M8 and M12 sensor connectors used for fieldbus and sensor networks, among others.
Data connectors or Data connectors are specifically designed for fast and trouble-free data transmission. They play a critical role in bus systems and industrial networks where high transmission speeds and EMC (electromagnetic compatibility) protection are required. These include, among others, RJ45 connectors used in Ethernet-based networks and M12 X-coded connectors used for Industrial Ethernet.
Industrial connectors are specially designed plug-in connectors used in harsh, demanding environments. They are rugged, resistant to dirt, moisture, vibration, and temperature fluctuations, and provide a reliable electrical connection for energy, signal, and data transmission. Industrial connectors can be categorized not only by transmission type, but also by their design. The two main designs that differ in design, functionality and application are round plug connectors and rectangular connectors.
Round plug connectors or round plugs are compact, robust, and offer a high degree of protection against environmental influences, which is why they are primarily used in sensor technology, mechanical engineering and communication technology. Rectangular connectors or Rectangular plugs, on the other hand, are usually modular, mechanically stable, and designed for high current and signal transmissions, making them ideal for control cabinet construction, automation technology and plant engineering.
Connectors are coded to prevent misconnections, increase safety, and facilitate installation and maintenance. In industrial plants, there are often multiple connectors of similar construction, but they perform different functions, such as for power, signal or data transmission. Coding ensures that only compatible plugs and sockets can be connected to each other. In common applications, coding is defined by standards to ensure consistent and reliable use. There are two main types of coding:
Industrial connectors or Industrial plugs ensure a reliable electrical connection between various components and often have to withstand extreme conditions such as vibration, dust, moisture, chemical influences or high temperatures. Because industry requirements vary widely, there are a variety of connector types that vary in design, technical specifications, and applications. Various technical and functional criteria must be considered when selecting the appropriate connector for an application. This includes, but is not limited to, the number of contacts, mechanical design, type of protection, electrical load capacity, and connection technology. The following sections detail some of these differentiators and selection criteria for industrial connectors.
A first important criterion when selecting an industrial plug is the current and voltage for which it is designed. Each connector has a maximum load limit specified in amps (A) for current and in volts (V) for voltage. These values must be tailored to the application to prevent overheating, voltage drops or even insulation failure.
The ampacity of a connector is highly dependent on the ambient temperature. As the temperature increases, the conductivity of the contacts decreases and the resistance increases, resulting in additional heat generation. Therefore, the continuous current that an industrial plug can safely transmit must always be evaluated taking into account the actual ambient temperature. Likewise, the nominal voltage of a connector is often given only for a certain degree of contamination. The pollution degree describes how much a connector is affected by dust, moisture or other environmental influences. Higher contamination can cause leakage currents or voltage flashovers. Therefore, under such conditions, the permissible nominal voltage must be reduced.
Another important selection criterion for industrial connectors is the number of wires or Pins. This determines how many electrical connections can be realized within a plug. In principle, the following applies: The more pins a connector has, the more signals or different voltage levels can be transmitted via a single connection. 4-pin or 5-pin industrial connectors are used primarily for simple sensor/actuator connections, since only one power supply and one signal are usually required here. 16-pin industrial connectors, in turn, are used in complex control, signal, and power applications, such as in servo motors or control systems, where numerous electrical signals must be processed simultaneously.
Plug-in connectors must work reliably in demanding environments. Protective mechanisms are designed to protect connectors from moisture, dust, mechanical stresses, and electromagnetic interference to increase durability and operational reliability. A central aspect is the type of protection, which is defined according to the IP protection classes (IEC 60529). These indicate to what extent a connector is protected against the ingress of solids (e.g., dust) and liquids (e.g., water or oil). The protective mechanisms and housing materials are also used to protect the industrial connectors from corrosion.
In addition to mechanical protection, electromagnetic compatibility (EMC protection) is also important. Industrial connectors may be equipped with metallic enclosures or shield contacts to protect sensitive signals from electromagnetic interference (EMI) or radio-frequency interference (RFI). This is especially important for data and communication connections, for example in Industrial Ethernet or bus systems, where noise can lead to signal loss or data errors.
When installing industrial connectors, a safe, durable, and reliable connection between electrical components must be established. Connectors can be mounted using different mounting techniques depending on the type and application. A particularly reliable and durable method is crimping, which compresses wires with crimp contacts – ideal for industrial applications with high mechanical requirements. Precise crimping and pressing tools are essential for this. Another common technique is soldering, which establishes a fixed and conductive connection between the cable and contact, in particular for electronic components and PCB connectors. For a safe and professional solder connection, MISUMI offers the right soldering supplies. Both methods provide a reliable solution to safely and permanently mount connectors.
