Concept and Application

Safety devices are typically used to safeguard any machine, equipment and human life from electric shocks.Relays are the heart of any safety system.

Relays are basically protection or switching devices that isolates a system when the electrical current exceeds a limit. Thereby protecting the system from getting damage. This system can be an equipment or human body.All the relays respond to one or more electrical quantities like voltage or current.

There are various types of relays.

  1. Electromagnetic Relay
  2. Solid State Relay
  3. Hybrid Relay
  4. Thermal Relay
  5. Reed Relay, etc.

How does Relay work:

These Relays generally consists of Coil, Contact, Soft magnetic components, Permanent magnet (may or may not be present) Spring (may or may not be present)

Relay Close Socket Relay Open Socket

When a relatively low current (secondary) is passed through the coil, the magnetic field attracts the contacts and the primary circuit is Opened. The current passed through the coil is a result of increase in primary current over set limit. In case of GFCI (Ground Fault Circuit Interrupter), this secondary current is due to difference in leakage of current in primary current (may be due to electrical shock). Thus saving the primary circuit (Equipment and Human life) from getting damaged.

Since, high permeability is required for relay to actuate precisely, these parts are generally made in 48% NiFe The contacts and soft magnetic components need to have very good surface finish and excellent magnetic properties.

PML provides these parts with Surface Finish:

  • Roughness value(Ra) = 0.02 microns max.
  • Flatness = 1 light band max.

Magnetic properties:

  • For 45% Ni:Fe : AC Permeability at 5 mOe = 12000
  • For 80% Ni:Fe : AC Permeability at 40 gauss = 85000

Because of such stringent surface requirements, there parts are to be tested in a very clean atmosphere. PML checks the parts in Class 100 clean environment.

What we can offer:

Relay Relay GFCI Core
  • Relays for Human safety
  • GFCI (Ground Fault Circuit Interrupter)
  • Auxiliary Relay for Machine safety
  • CBCT (Circuit Breaker Current Transformer)
  • Relays for Gas meters
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