Home » Methods to Reduce Step Potential and Touch Potential in Substation
Switchgear & Protection

Methods to Reduce Step Potential and Touch Potential in Substation

Step Potential and Touch Potentials are very important in substations because during ground faults all the ground current returns to the substation transformer (as the substation transformer is grounded). The current that returns through the earth can create a significant voltage gradient along the ground and between ground and conducting objects.A step potential in substationcreates a path through the legs from one foot to the other. A touch potential in substation is normally considered a hand-to-foot or hand-to-hand contact.

Step potential and touch potentials are of concern during normal conditions and during ground fault.Under normal conditions, unbalanced currents can rise the neutral to earth voltage. This is not normally dangerous but it can cause shocks.

Step potential and Touch potentials during faults are more dangerous. Therefore it is important to reduce the step potential and touch potential to be within limits during the substation design.

Methods to Limit Step Potential and Touch Potential:

Step potentials and touch potentials can be reduced by employing one of the following methods:

  1. By proving low resistance path to ground
  2. By providing insulation layer between operating personnel and earth
  3. By proper placing of ground conductors

Some of the methods employed to reduce step potential and touch potential in substation  are:

  • Multi-grounded neutral helps to reduce the dangerous step potential and touch potential during line-to-ground faults. By creating low impedance path back to the source, faults are quickly cleared by fault interrupters. Multiple grounding electrodes tied together helps to reduce the touch potentials at the fault point. With multiple neutrals, step potentials are usually not dangerous since fault currents spreads between several grounding electrodes
  • Using a reactor on the substation transformer neutral helps to limit the step and touch potentials. While utilities normally use the neutral reactors to limit the fault currents. the reduction of ground fault currents also reduce the step and touch potentials and reduces current in grounding and bonding connectors.
  • By wearing electric hazard shoes. These shoes when dry can have offer millions of ohms of resistance which can save the operating personnel against these dangerous potentials. By using insulating materials such as rubber gloves can protect the personnel.
  • By providing resistive surface layers in and around the substation. It is often provided with the surface of crushed rock or pebbles which acts as insulation medium between the operating personnel and earth.

Related Articles

Substation Safety Clearances

S Bharadwaj Reddy

Advantages & Disadvantages of Oil Circuit Breakers

S Bharadwaj Reddy

What Is Step and Touch Potential and Reducing Resistance To Ground?

S Bharadwaj Reddy

Sulfur Hexafluoride Gas (SF6) Properties

S Bharadwaj Reddy

Advantages and Disadvantages of Air Blast Circuit Breakers

S Bharadwaj Reddy

Advantages & Disadvantages Electromagnetic Relays

S Bharadwaj Reddy

1 comment

Jacque Jr LOUIS December 23, 2019 at 12:48 pm

Very interesting website


Leave a Comment

This website uses cookies to improve your experience. We'll assume you're ok with this, but you can opt-out if you wish. Accept Read More

Methods to Reduce Step Potential and Touch Potential in Substation

WordPress Image Lightbox

Send this to a friend