Round connector

What are circular connectors?

Circular connectors are so-called due to their "round" shape. They comprise an enclosing housing made of plastic, metal, stainless steel or brass in which the connection element can be found. These connection elements comprise a socket and a pin side, and are coded in such a way that they only fit on the respective matching mating piece. On the rear, the circular connectors have the connections for the cables via which the individual contacts are connected. These contacts are either firmly installed in the connector or need to be ordered separately and mounted using a crimping tool, as is the case with circular connectors for crimping. Circular connectors are mainly used in measuring technology, control technology and regulation technology as well as in automation and mechanical engineering. 

Selection criteria for the right circular connector

How do you find the right circular connector? In most cases, the size (M5 - M58) is predefined. For new installations, however, you may also have to select the circular connector according to the type (signal, power or data transmission). It also depends on the environment in which the connector is used. The connection technology, material and design play a decisive role here. We have listed the decision criteria for you below, which you can use to select your customised circular connector.

Sizes of circular connectors

Circular connectors are available for applications in industrial electronics in the following sizes:

• M8 circular connectors
• M12 circular connectors
• M16 circular connectors
• M17 circular connectors
• M23 circular connectors
• M40 circular connectors
• M58 circular connectors
• 7/8“ circular connectors
• R15 circular connectors
• RD24 circular connectors

Selection-criteria

Circular connector designs

All types are DIN circular connectors which have pins arranged in a circle in accordance with the DIN standard. A distinction is made between the data connector, power connector, signal connector and hybrid connector types.

Data connectors: As the name suggests, this type is used for the safe and reliable transmission of data. The data connectors usually have an M8 or M12 thread and are used in field bus systems and networks.

Power connectors: The power connectors are used for voltages of up to 630 V and a rated current of up to 150 A. The most common type is the M23 circular connector. However, power connectors are also available in thread sizes M12, M17, M40 and M58. 

Signal connectors: Signal connectors are used in industry to read out sensors and control actuators in a targeted way. The circular connectors of sizes M17 and M23 cover a wide range of industrial signal applications. They also include requirements in terms of tightness, vibration resistance and EMC protection.

Hybrid connectors: Hybrid connectors transmit both signals, power and Ethernet in one single connector. This keeps the connectors extremely compact and saves you time and space when connecting.

Designs / types of circular connectors

The designs or types of circular connectors are distinguished as follows:

• Power connectors
• Signal connectors
• Hybrid connectors
• Data connectors

Connection technologies and material for circular connectors

There are different connection technologies available depending on the application for the circular connectors. The three most common connection technologies are:

• crimp connection
• solder connection 
• screw connection

The most common materials for circular connectors include

• plastic
• metal
• stainless steel  

Circular connectors designs

A distinction is made between the designs in terms of the following points:

• straight design
• angled design 
• for rear wall mounting 
• for front wall mounting 
• different numbers of pins from 3 to 19 
• different codings 
• different rated voltages

Circular connector thread sizes

The different thread sizes for circular connectors are indicated by the marking M (metric) plus a number, e.g. M8 circular connectors or M12 circular connectors. In addition, M16 circular connectors, M17 circular connectors, M23 circular connectors, M40 circular connectors and M58 circular connectors are available, which have different power transmission properties.

Other types such as the RD24 circular connector have a screw connection and ensure strain relief with a clamping cage. The R15 circular connector is a device connector that has a socket with crimp connection. The robust 7/8"" circular connectors are suitable for high power transmission, particularly in mechanical engineering. 

Circular connector locks

The requirements on a lock are high, since it should be able to be locked and released again quickly and easily during assembly. There are various different locks available which fulfil these requirements:

1. Circular connectors with bayonet lock: This is a quick mechanical connection tat can be made and released by inserting the connectors into each other and turning them in opposite directions.
2. Crimp circulator connectors: When crimping, the plastic deformation gives the connection a good hold. If necessary, it can be released and renewed with a circular connector crimping tool.
3. Circular connectors cable gland: The classic version of a solid connection is equipped with a screw lock. This means that the connector is optimally protected against vibrations and cannot be released accidentally.

Circular connector manufacturers

There are many manufacturers on the market, whose large product range covers the most versatile requirements on a safe connection.

• Phoenix Contact circular connectors are available in different categories such as data connectors, power connectors, signal connectors and hybrid connectors.
• Harting circular connectors are available in numerous versions with standard screw locks or innovative push-pull locks.
• As a successful manufacturer in connection technology for decades, Amphenol supplies circular connectors in different versions.
• As an innovation driver, the Hummel circular connectors cover all types of applications and can be found in numerous applications in industry.

Circular connector materials

In order to react to the respective application environment, circular connectors are available in different materials. Thus circular connectors made of metal protect the sensitive contacts in the connector against impact, while circular connectors made of plastic are almost as robust as metal and are used as a reliable variant for standard applications in mechanical engineering. Wherever special hygienic regulations apply or there is a harsh environment such as in industry, for example, circular connectors made of stainless steel are used.

Which numbers of pins are available for circular connectors?

Pins in the connectors transfer the required information and make a compact cable possible even where space is tight. Thus 4-pin screw-on connectors or 4-pin circular connectors ensure reliable data transmission, for example. Common numbers of pins for circular connectors include 2-pin, 3-pin, 4-pin, 5-pin, 6-pin, 7-pin, 8-pin, 10-pin, 12-pin and 17-pin.

IP protection class for circular connectors

IP protection class means “International Protection” and describes a protection class which specifies whether and how the respective circular connectors are protected in terms of the technology and the components installed. The figures indicate which protection class is involved.

• Circular connectors IP65: dustproof, suitable for water jets
• Circular connectors IP67: dustproof, suitable for temporary submersion in water
• Circular connectors IP68: dustproof, suitable for permanent submersion in water

Overview diagram of circular connectors Selection criteria for the suitable circular connector

How can you find the suitable circular connector? Usually, the size (M5 - M58) is specified. However, with new installations you may need to select the circular connector on the basis of its design (signal, power or data transmission). In addition, it depends which environment you wish to use the connector in. Here, the connection technology, material and design play a decisive role. In the following, we have listed the decision criteria for you on the basis of which you can select your individually suitable circular connector.