Immunity to Electrostatic Discharges

Immunity to electrostatic discharge

The tests for electrostatic discharges (ESD), have as objective to establish a common test structure that is reproducible, in order to be able to evaluate the behavior of the different equipment under test (EUT) subject to ESD. Data to take into account when establishing the tests to be carried out:

  • Check the operation of the equipment when applying levels of electrostatic discharge disturbance that simulate those produced by the operators in their direct action on the equipment or indirectly, through adjacent objects.
  • Two bodies with different dielectric constants when rubbed produce an exchange of charges between them, in such a way that they are charged. When one of them comes into contact with a body with low resistance to ground, it is discharged through it until both potentials are equalized.
  • In the case of a person, it is charged due to the exchange of loads between the sole of his shoes and the ground he walks on or because of the friction in the clothes. When this person touches a computer, the discharge jumps, flowing through the equipment to the ground, causing serious damage to the internal electronic circuits.

There are two types of electrostatic discharge:

1) Direct downloads on the equipment

  • Contact discharges, in which the tip of the generator remains in contact with the equipment under test.
  • Arc jump downloads, which simulate the approximation of the finger of a hand to the equipment under test.

2) Indirect downloads

  • On coupling planes to simulate the effects of discharges produced on equipment or objects adjacent to the equipment under test.

Levels: Depends on the standard, from 2kV to 8 kV contact; and from 2kKV to 15kV of air.

⇒ Criterion: After the test the equipment must be able to operate without degradation or loss of function. During the test a certain degradation of the operation is allowed (criterion B, normally).

Inmunidad a Descargas Electrostáticas

Trial configuration

Radiated RF field

  • Apply an amplitude modulated signal (1 kHz – 80%) on the equipment in the 80 MHz – 2.7 GHz frequency range.
  • Radiated RF electromagnetic energy fields are intentionally produced by TV stations, AM / FM radio stations, telephone base stations, citizen band equipment, mobile phones, etc.
  • Another type of equipment that produces RF electromagnetic energy radiated unintentionally, are the inductive load switches, arc welding equipment, fluorescent lamps, etc.

⇒ Levels: Depends on the standard, from 1 V / m to 30 V / m.

⇒ Criterion: During the test the equipment must be able to operate without degradation or loss of function (criterion A, normally).

Inmunidad a Descargas Electrostáticas

Calibration configuration

Electrical transients

  • Check the operation of the equipment when applying bursts of repetitive electrical transients on AC, DC, signal and telecommunications power lines.
  • The electrical transients and / or bursts are generated by switching maneuvers in the interruption of inductive loads, contact rebound in relays, motors, compressors, etc.
  • Another type of equipment that produces RF electromagnetic energy radiated unintentionally, are the inductive load switches, arc welding equipment, fluorescent lamps, etc.

⇒ Levels: Depends on the standard, from 500 V to 4 kV.

⇒ Criterion: After the test the equipment must be able to operate without degradation or loss of function. During the test a certain degradation of the operation is allowed (criterion B, normally).

Nourishment

Inmunidad a Descargas Electrostáticas

Networks of coupling / decoupling

Signal, data and controlInmunidad a Descargas Electrostáticas

Inmunidad a Descargas Electrostáticas

Redes de acoplo/desacoplo

Shock waves

  • Check the operation of the equipment when applying surge and overcurrent impulses on power lines AC, DC, telecommunications, signal and control.
  • Unidirectional shock waves are caused by transient overvoltages of the lightning or switching type.
  • The effect of a direct lightning strike on the equipment is not considered.
  • Application: In common and differential mode. In the case of AC it is coupled in the angles.

⇒ Levels: It depends on the standard, from 500 V to 4 kV.

⇒ Criterion: After the test the equipment must be able to operate without degradation or loss of function. During the test a certain degradation of the operation is allowed (criterion B, normally).

Line – Line

Inmunidad a Descargas ElectrostáticasTest configuration – Capacitive coupling AC / DC lines

 Line – Earth 

Inmunidad a Descargas ElectrostáticasTest configuration – Capacitive coupling AC / DC lines

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