Dielectric Strength

Dielectric strength measures the electrical strength of a material as an insulator. It is defined as the maximum voltage required to breakdown a specific material and is expressed as volts per unit of thickness. The higher the level of dielectric strength, the higher the quality of the insulator, and thus the ability of the coating to withstand or resist the passage of an electrical current.

There are three basic procedures used to determine dielectric strength, including short time, slow rate of rise and the step-by-step method. For each methodology, a specimen is placed between two electrodes in either air or oil. The voltage required to breakdown the material is then determined by the time the material takes to breakdown dielectrically.

When you are testing the effectiveness of a device's electrical insulation there are essentially three things you are assessing to help ensure insulation resistance along with device safety and performance.

  1. Keep conducting plates from contacting one another
  2. Increase effective capacitance while reducing electric field strength, i.e. same charge with a lower voltage 
  3. Reduce the possibility of shorting out via sparking during high voltage operations.

Medical Industry Applications of Dielectric Strength

Dielectric strength is measured in the medical industry when insulators are required for particular tools, devices and equipment to help isolate electrical currents, or live parts, from patients and medical staff.

Medical Safety Considerations of Dielectric Strength

The most important safety consideration tied to dielectric strength in the medical field is the safety of the patient and safety of the operator of the device, such as the doctor, nurse or other medical staff. Therefore, the insulating properties, or dielectric strength, of a given device or piece of equipment also relies on a perfectly closed system, without interference from outside variables, to help reduce safety risks and promote proper use.

The dielectric strength of materials, including the design of the device, is also an important consideration when a medical device or piece of equipment is connected to a power source or supply, as are external variables such as temperature, humidity and air pressure. In addition, the exact insulating variances and standards will depend on the materials and intended use of the device.