Circular connectors

Circular connectors are plug connectors with a round or cylindrical design that allow power and signal cables to be plugged together with a device or machine. Thanks to their robust design and low space requirements, they are ideal for industrial environments. The EPIC® circular connector portfolio offers the right product for the two transmission types of signals and power: EPIC® SIGNAL for signal transmission and EPIC® POWER and EPIC® POWERLOCK for the power supply of devices, machines and plants. We offer single or multi-pin circular connectors in various variants – as individual parts, kits or as customised assemblies.

A connector as an important component in electrical engineering enables you to easily connect cables to an equipment and detach them again at any time.

Electrical connectors are available in every conceivable design. In addition to circular connectors, viewed from the front, rectangular, oval and trapezoidal connectors are common on the market. Connectors with a circular connector face are also used in the domestic sector. Every traditional household socket is round. But what is the difference between circular household connectors and circular industrial connectors?

If there is no specific standard, industrial connectors are developed and tested in accordance with IEC 61984. The standard refers to "connectors", while the term plug is commonly used. This connector standard takes into account the higher requirements for electrical connectors used in industrial applications. For industrial connectors, higher-quality materials are usually used compared to the cost-effective household connector. Industrial connectors tend to have higher power reserves. They are also more robust and better protected against harmful environmental influences.

But not all circular connectors are the same! In the EPIC® circular connector product group, we at LAPP offer you an extensive product portfolio so that you can find the perfect circular connector for your application. The circular connectors are also known by their designation for the respective product family, such as M12 circular connectors or M23 circular connectors. Delve into the interesting world of circular connectors and become an expert when it comes to circular connectors!

Certain circular connectors have established themselves in some industrial applications. The M17, M23, LS1, LS1.5, LS3 families are very often used in electric motors, especially servo motors. The advantage is obvious: the connector for this application must be as small as possible, resistant to vibration, robust, EMC protected and also resistant to moisture, oils and dust. This is why EPIC® circular connectors from LAPP are used very frequently in servo assemblies. Due to their advantages, circular connectors can be found in a wide range of industrial environments where automated control of complex processes plays an important role:

• Mechanical engineering
• Energy technology
• Production systems in the automotive industry
• Conveyor technology
• Food industry
• Industrial robots

For example, you have certainly seen a bottling plant that fills drinks in bottles independently and automatically. Thanks to the built-in control electronics, the positioning axes of the filling plant work with precision down to the millimetre so that the liquid does not end up next to the bottle, but rather instead inside it. To make it possible to fill smoothly, the individual process steps are precisely coordinated with one another. They always run the same, even after millions of cycles. In a system like this, servo motors are used that supply energy and transmit data and signals – with circular connectors!

Do you find servo drives exciting?
>>Find out more about servo drives and their use here!

Circular connectors are available as single and multi-pin power connectors and as multi-pin signal connectors. Our EPIC® circular connector portfolio is divided into three product segments:

1. signal connector: EPIC® SIGNAL

EPIC® SIGNAL circular connectors transmit all kinds of signals reliably. In the example of the servo motor, the feedback and resolver signal from the servo motor are transferred completely securely from the EPIC® signal connector. The robust connection system prevents signal transmission interruptions thanks to the precisely coordinated and high-quality gold-plated contact system, even in the event of vibrations and lower currents and voltages.

The EPIC® SIGNAL connectors provide reliable protection against electromagnetic interference thanks to their full metal housing and an integrated EMC cable gland. The shielding braid of the cable is precisely and securely connected to the connector. The currents created in the cable shield by electromagnetic radiation or potential difference are thus safely diverted via the connector.

EPIC® SIGNAL connectors are available in sizes M17, M23 and R3.0 (M27).

2. Power connectors: EPIC® POWER
   Maximum performance in the smallest installation space. This is the essential feature of EPIC® POWER circular connectors. Like the EPIC® SIGNAL circular connectors, an EMC cable gland with strain relief is integrated. The current is transmitted via gold-plated or silver-plated contacts. Silver is electrically the best conductor; however, a gold surface is preferred for the smaller contacts as it does not start to degrade, even after years. All EPIC® POWER connectors are equipped with a protective conductor contact that enables the green/yellow or green protective conductor to be connected.

EPIC® POWER connectors are used in harsh industrial applications where the outer dimensions of the plug need to be as small as possible. The servo motor application is also typical here. These motors can be found in robotics applications, all kinds of production machines and even plants that need to be small. EPIC® POWER connectors are available in sizes M12, M17, LS1 (M23), LS1.5 (M40) and LS3 (M58).

3. Power connector: EPIC® POWERLOCK
   With EPIC® POWERLOCK you will find single-pin circular connectors that are suitable for transmitting very high currents and are used for supplying power to mobile generators and machines, for example, as well as stationary power stations for inland shipping and for supplying power at event venues.

EPIC® POWERLOCK circular connectors are single-pin and are colour-coded and geometrically coded to prevent incorrect connections. EPIC® POWERLOCK connectors are suitable for applications up to 400 A (screw connection) and 660 A (crimp termination).

EPIC® circular connectors have a very compact design. The common series are fully metallic and also metallically conductive. This is important for good protection against electromagnetic interference. Unwanted currents on the cable shield are thus diverted via the metallic conductive plug. The circular connector design also provides seals on the inside and thus provides better protection against mechanical and chemical influences.

The industrial environment in which circular connectors are used requires a robust design that can withstand damage from liquids, dirt, extreme temperatures and mechanical influences. Circular connectors can thus be used for applications in harsh environments where reliable components are required.

Are you not sure whether circular connectors are the best choice for your application?
>>Learn more here about other connector types!

Each connector design consists of a housing, an insert (also known as the insulating body) and the matching male or female contacts.

The main function of the housing is to protect the electrical connection and the contacts. Environmental influences such as the penetration of foreign bodies (dust), liquids (water, oil or chemical substances) or the ambient temperature can impair the electrical connection. The housing also serves for mechanical stability, i.e. its ability to withstand mechanical influences such as external shocks and vibrations that can facilitate tear, breakage, wear or other damage.

The housings for our EPIC® circular connectors are made of metal or plastic. The metal housings have a conductive coating. This design ensures that the actual electrically conductive part of the connector is safely protected against electromagnetic interference. The plastic housings do not offer the option of connecting a cable shield and are therefore used with unshielded cables. However, the high-quality plastic also provides excellent protection against mechanical and chemical influences.

The contact insert is used to securely hold and secure the contacts. Here, the quality of the plastic used and a solid design of the contact insert are crucial for a long and reliable service life. Thanks to high-quality materials, leakage currents along the plastic surface are minimised and disruptive discharges are safely prevented.

The contacts – the actual current transmitters – are fixed in the contact insert. These are floating to compensate during connection and to minimise insertion forces. The contact area where the male and female contacts meet (between two connectors) and the contact area where the conductor is connected to the contact (between the cable and connector) are particularly important.

The way contacts are arranged in a contact insert is referred to as a pole configuration. The number of poles available depends on the number of contacts that can be used in a connector. Only as many contacts as there are maximum poles can be installed. If a pole configuration has, e.g. 7 poles, up to 7 contacts can be installed – but not more.

EPIC® circular connectors are available with different pole configurations, which result from the different configuration, number and type of contacts.

Generally the following applies:

Number of contacts and rated voltage	Contact diameter and currents
The more contacts are installed in a given connector housing, the lower the rated voltage for which a connector is designed can be. This means that the shorter the distance between the contacts, the lower the maximum voltage that can be applied to the plug.	As the contact diameter increases, the maximum possible current also increases (but other factors such as the contact material and the contact coating must also be taken into consideration).

For circular connectors, it is not only the number of poles, but also the type of conductor you want to connect to the circular connector. A distinction can be made between two types of conductors:

• Conductors for working contacts.
• Protective conductors (PE = protective earth): serves as safety and protects against electric shock. In the metallic housing, the protective conductor is conductively connected to the housing. The protective conductors are also pre-manufactured, i.e. it contacts first when being inserted and then disconnects last when being disconnected.

The pole configuration and pole configuration designation of a product allows you to read not only the number of contacts, but also the type of conductor that can be connected to it. If contacts of different design and diameters are provided for the working contacts, they are listed individually, such as in pole configuration 3+PE+4.

To explain: a total of eight contacts are included in one connector with a pole configuration of 3+PE+4. Three thicker contacts for power supply, one contact for protective conductors and four thinner contacts for signal transmission.

Example pole configuration designations and their meaning

Product	Pole Configuration designation	Pole Configuration	Description
EPIC® SIGNAL M23	7		Circular connector insert with 7 working contacts   P = counter-clockwise (Anticlockwise connection view)
EPIC® SIGNAL M23	7		Circular connector insert with 7 working contacts   E = clockwise (clockwise connection view)
EPIC® SIGNAL M23	8+1		Circular connector insert with 9 working contacts for 1 thicker contact and 8 thinner contacts   P = counter-clockwise (Anticlockwise connection view)
EPIC® SIGNAL M23	8+1		Circular connector insert with 9 working contacts for 1 thicker contact and 8 thinner contacts E = clockwise (clockwise connection view)
EPIC® POWER M17	3+PE (2 mm contacts)		Circular connector insert with 3 working contacts and 1 PE contact
EPIC® POWER M17	3+PE+5 (1mm/0.6mm contacts)		Circular connector insert with 8 working contacts for 3 thicker contacts and 5 thinner contacts 1 PE contact

The EPIC® circular connectors are available in a wide range of variants. Its external appearance – i.e. whether a circular connector is straight, angled, with a coupling nut or outer thread, with or without a fastening flange – is called the design. Use our design overview to find the right design for your application.

Design	Fig. (dependent on product)	Designation	Use	Can be used with
A1		Panel-mount base	Front wall-mounting	D6
A3		Panel-mount base, angled, rotatable	Front wall-mounting	D6
A6		Panel-mount base for female contacts	Front wall-mounting	F6
B1		Panel-mount base with threaded boreholes	Rear wall-mounting	D6
B2		Panel-mount base with through bores	Rear wall-mounting	D6
C2		Feed-through connectors	Housing assembly, for connecting two M23-D6 cable connectors	D6
D6		Cable connectors	for cable extensions	A1, A3, B1, B2, C2, G4, G5, F6, F7
F6		Coupling couplers	for cable extensions	D6
F7		Cable coupler with fastening flange	For cable extensions on a device wall	D6
G4		Panel-mount base	Front wall-mounting for threaded borehole	D6
G5		Panel-mount base	Front wall-mounting for through bore	D6
G6		Panel-mount base	Back wall-assembly for through bore	D6

Suitable accessories below!