High-Voltage Connectors: Types, Characteristics, and Safe Usage

High-voltage connectors allow easy installation/uninstallation of high-voltage wiring, eliminating the need for screw fastening employed in normal wiring connections. Thus, high-voltage devices (e.g., X-ray tubes, PMTs, piezo, MCPs, electron beams, and ion beams) can be easily changed or replaced, and equipment can be easily moved or relocated. Wiring connections can be made quickly and easily by using high-voltage connectors for changing and moving around equipment in laboratories, facilities, and factory production lines.

There are many types of high-voltage connectors and applications for high voltages, including the transmission of electrical power and use of high voltages in medical and scientific applications. High-voltage connectors are used for easy connection and disconnection when installing wiring to send high-voltage electricity from a power source to a device. They can be classified into three main types depending on the type of high-voltage cable used.

• Non-shielded high-voltage cable connectors

These include high-voltage connectors used for single-core high-voltage cables without a shield, high-voltage silicon cables, and high-voltage Teflon cables. There is no general standard, and instead specialized connectors unique to high-voltage devices and connector makers are used.

• Coaxial high-voltage cable connectors

High-voltage connectors such as BNC, MHV, or SHV are used for connecting shielded single-core coaxial cables. Although other connectors for coaxial cables, such as SMA, SMB, and SMC, can be used, they cannot be used for very high-voltage applications. There are also proprietary high-voltage connectors of connector manufacturers that are used as de facto standards in certain applications.

• Multicore high-voltage cable connectors

Multicore high-voltage cable connectors are used for X-ray tubes, electron beams, ion beams, etc. For medical X-ray equipment, connectors are standardized by JIS or other similar standards.

Common types of high-voltage connectors include

Miniature High Voltage (MHV)

The MHV connector, sometimes referred to as BNC-HV, is designed for high-voltage coaxial connections. While it shares a similar bayonet locking mechanism with standard BNC connectors, MHV is engineered to handle significantly higher voltages.

Safety Note: MHV connectors can physically mate with standard BNC receptacles despite the voltage mismatch. This poses a significant safety risk. Consequently, many modern safety standards recommend SHV connectors (which feature a protruding insulator to prevent accidental cross-mating) over MHV for new designs.

Safe High Voltage (SHV)

SHV connectors are high-voltage connectors for coaxial cables that can be used at higher voltages than MHV connectors. The plug of the SHV connector is designed such that the insulation surrounding the center of the coaxial section protrudes beyond the center electrode, thereby increasing the creepage distance between the center contact and the outer conductor shield.
Therefore, they cannot be connected to MHV or BNC connectors.

Summary of high-voltage connectors for coaxial cables

High-voltage connectors for coaxial cables include BNC, MHV, and SHV connectors, as well as HN connectors and manufacturer-specific connectors. The specifications of these connectors are summarized below. Please verify the required specifications prior to use as they may differ among different manufacturers. Coaxial cable high-voltage connectors are used in probe-type survey meters (radiation detectors), for example, to connect the probe to the main unit with a coaxial cable.

High voltage connectors for coaxial cables

Type	BNC	MHV	SHV	HN
Rated voltage *	500 Vrms	1600 Vrms	3500 Vrms	1500 Vrms
Impedance	50 Ω	50 Ω	50 Ω	50 Ω
Frequency	DC to 4 GHz	DC to 300 MHz	DC to 300 MHz	DC to 4 GHz
	Bayonet	Bayonet	Bayonet	Threaded
Standard	JIS-C-5412, MIL-C-3608, MIL-C-39012	MIL-C-39012	MIL-C-39012	MIL-C-3643

Precautions for use The shape of the MHV connector is very similar to that of the BNC connector. Care must be taken not to interchange them.
* The rated voltage is the standard.
High-voltage versions MHV and SHV are available from connector manufacturers.
At Matsusada Precision, MHV and SHV connectors with higher voltage ratings are used for products that output higher voltages than the specified rated voltage.
When using MHV or SHV connectors and cables from other manufacturers, please pay attention to specifications such as operating voltage.
We supply cables with MHV connectors and SHV connectors.

The major difference between using low- and high-voltage electricity is that one must be more careful about safety when using high-voltage electricity. The dangers of commercial 100 V lines are incomparable to those of high-voltage electricity. Therefore, it is imperative to carefully check whether the electrodes are exposed. Depending on the high-voltage connector, if it is not plugged in carefully, the pins may bend and the terminals may contact each other, causing a short circuit or even disconnection. Therefore, it is necessary to thoroughly check the connector terminals for bends or deformations during routine maintenance and prior to connection.

Even if the standards are different, some connectors can be connected via forced insertion. This situation tends to occur when the shapes of the connectors are similar. Additionally, wiring mistakes can occur if there are multiple connectors. In this case as well, a short circuit or miswiring of the high-voltage circuit could cause a failure that could result in complete destruction of the equipment.
Moreover, when the surfaces of the plug and receptacle become dirty, creepage discharge may occur owing to their high-voltage characteristics. Therefore, connectors should be periodically cleaned to prevent insulation failure. Grease is generally used in R24 type connectors; hence, they must be greased periodically.

Other problems include sharp metal debris on high-voltage cables and connectors, which can create holes in the insulating material and cause short circuits. If there is a flammable object in the vicinity, a fire may ensue. High voltages can efficiently transmit a significant amount of energy, but a misconnection or short circuit can have severe consequences; therefore, appropriate measures must be taken to prevent such mishaps.

When the same amount of power is used, a higher voltage will reduce the current. If the current is low, the size of conductors used in the circuit can be reduced, which results in weight savings and the suppression of heat generation. However, high voltage, instead of low current, increases the risk of arcing between closely spaced conductors just by the proximity of the positive and negative wires. When using high-voltage electricity, maintaining an appropriate wiring distance is an important design factor. There will be cases wherein the wiring will not function the same way as low-voltage wiring. Along with understanding the dangers of high voltages, it is necessary to try to take advantage of their benefits because they can transmit an enormous amount of power with little current.

To distinguish between conventional 12 V and 24 V lead-acid battery wiring in hybrid vehicles and BEVs, the high-voltage circuits are composed of orange cables for easy identification. Orange cables are used for wiring lithium-ion batteries, motors, inverters, and onboard chargers.

To ensure safety and electromagnetic compatibility (EMC), high-voltage circuits in electric vehicles primarily use shielded high-voltage cables, identified by their orange insulation. These cables connect critical components such as lithium-ion batteries, motors, inverters, and onboard chargers.

As the industry moves toward higher charging speeds and voltages, the demand for robust high-voltage interconnects capable of handling high currents while maintaining shielding effectiveness is rapidly increasing.