Electrical Connectors


  • Review the function of a connector
  • Demonstrate the use of common connectors
  • Explain the different configurations of connectors
  • State best practices for connector inspection and maintenance

What Is a Connector?

A connector (also known as a physical interface) is a device for joining different parts of electrical or optical circuits. Basic connectors have two parts: plugs (male) and jacks (female).

Some connectors can be easily connected and are usually used on external cables. There are also system integrated connectors that may require a tool for removal and assembly.

There are many types of common electrical connectors, but in this lesson we will be focusing on the commonly used industrial electrical connectors.

Connector Terminology

The two halves of a basic connector are typically referred to as male and female, as a direct analogy to human physiology. The male connector typically has one or more protrusions that fit inside a female connector. This is done to ensure safety and proper functionality when connecting (mating) the two parts together.


With electrical connectors, the gender may not be obvious. Sometimes the connector that appears to be male, actually has pins inside, and even though the female connector appears to be male, the protrusion actually has holes in it to receive the pins from the male connector.

A connector in a fixed location is called the jack and the portion that plugs into it is called the plug. Typically, the plug is male and the jack is female, but it’s possible for a male connector to also be a jack, and a female connector to be a plug. This can cause some confusion, so it’s best to use male and female to describe the gender of the connector only, and to use plug and jack to describe whether it’s fixed or mobile.

The connector on the left (Jack) has the ability to be mounted in a fixed location whereas the connector on the right (Plug) is mobile. In this case, the jack is male and the plug is female.

Schematic Symbol

This is the typical symbol used for connectors. Below are some examples of other ways a connector might be represented on a schematic.

Schematic Symbol for Electrical Connectors

Example Schematics

The connectors are circled in red on the schematics.

Types of Connectors

There are many types of electrical connectors that are used for power, data, signal or control.

Power connectors are used to connect a power source to different system components.

Data connectors are used to connect data processing modules together.

Signal connectors are used to connect high frequency analog and digital signals.

Control connectors are used to connect control valves to hydraulic, pneumatic or electromagnetic actuators.

Connectors can be connected in many different ways including by pin or plug and socket, crimp, solder, and/or screw.

Pin/Plug & Socket Connectors are typically made up of a male plug and a female receptacle that when connected, complete the circuit.

Crimp Connectors are connected with special crimping pliers, that tightly compresses (crimps) an exposed wire to a connector.

Solder Connectors are joined by melting a metal filler to bond the two metal workpieces. The metal filler (solder) has a lower melting point than the two workpiece metals.

Screw Connectors are held tightened and held together by screw-type mechanism or set screw.

Common Connectors


Hirschmann is a brand that has many different types of connectors for industry including connectors used for power, data, and control.

Hirschmann Connector

Deutsch Connector


Deutsch is a brand that has a variety of power and signal connectors used in industrial applications.


Amphenol is another brand that offers a wide range of connectors for various power, data, and signal applications.

Amphenol Connector

Weather Pack Connector

Weather Pack

Weather Pack is a brand of extremely weather resistant connectors. They protect against extreme temperatures, dust, dirt and harsh chemicals, which makes them ideal for industrial and mobile applications.


Metri-Pack connectors have international standardized male blade sizes and are used in a wide variety of industries and applications. They are very similar to Weather Pack connectors, except that Metri-Pack are more likely to connect to a device and has less inline mating parts, making them very customizable and unique connectors.

Hirschmann Mini Din Connector

Solenoid Valve Connectors

Solenoid valve connectors are specifically made for controlling solenoids. The most common ones include the DIN 43650A, DIN 43650B, and DIN 43650C (mini DIN). The A, B and C refer to different sizes. DIN connectors are used to connect the solenoid operators of pneumatic and hydraulic solenoid valves to electronic controls.

Coaxial Connectors

Coaxial RF connectors are used to connect high frequency analog and digital signals. There are many variations in size and frequency to choose from, including BNC, UHF, TNC, SMA, Type F, and Type N. Some are threaded and are connected by a screw-type mechanism and others quick connect.

BNC Connector

Optical Fiber Connectors

Optical fibre connectors are used to connect parts of high speed optical signal processing system together. They also have a few variations in sizes and connection mechanisms.

Connector Inspection

Before disconnecting a connector for an internal inspection, be sure to check for proper installation, and any external damage or contamination.

Use a rag, brush and cleaning solution to clean the connector from the outside to prevent internal contamination.

If there are several similar connectors, label them before disconnecting them.

Once disconnected, inspect both sides of the connector:

  • Look for any liquid or solid substances inside.
  • Check for any signs of chemical or water corrosion.
  • Verify that the thread or lock is in good condition.
  • Check that the contacts are in the proper position and that the quality of the surfaces are good.
  • Looks for any signs of damage.
  • Check the condition of the internal and external seals.

Connector Maintenance

Ensure proper maintenance of connectors:

  • Use contact cleaner to remove any contamination.
  • Use compressed air to remove any residue.
  • Replace any damaged parts.
  • Use contact lube and sealing solution (if applicable).

Make sure the connectors are installed properly:

  • Check that the thread and locks are fully engaged.
  • Check that the external sealing is in good condition.
  • Make sure the connectors are aligned properly and that there is no significant tension or stress on the cable or connection.
  • Make sure there is a drip loop present for outdoor and mobile applications.

When replacing a connector you will need to know the basic parameters of the connector:

  • Number and arrangement of the contacts.
  • Size and gender of the shell, installation or mounting type.
  • Size and gender of the contacts.
  • Type of lock or thread.
  • Location of the configuration key.
  • Contact material and attachment method (solder, crimp, displacement).
  • Type and size of the cable seal and grip.
  • Special environment design (if required).


Label It

Drag and drop the labels to the correct targets on the image below.


Multiple Choice

What kind of connector is shown in the image?

What kind of connector is shown in the image?

What kind of connector is shown in the image?

What is this connector used for?


  • Connectors are devices used for joining different parts of electrical or optical circuits.
  • Industrial electrical connectors are used for power, data, signal and control.
  • Connectors are commonly connected by plug/pin and socket, crimp, solder, and/or screw.
  • Make sure to do an inspection for external damage or contamination before disconnecting connectors for maintenance or replacement.

We hope you enjoyed Electrical Connectors

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