What are the safety precaution in handling power supply devices?

Be sure to carefully observe the following safety precautions.

  • Always connect a ground wire. …
  • Do not touch high voltage areas. …
  • Cover high voltage areas. …
  • Share an awareness of danger. …
  • Perform operations with your right hand. …
  • Turn off the power before touching equipment. …
  • Pay attention to electric charge in cables.

What considerations have to be made when selecting a relay to use?

Consider these factors when choosing a relay for use in industrial controls:

  • Voltages driving loads are the first concern. The voltage rating of a relay must be greater than or equal to the voltage driving the load. …
  • The current required depends on the type of load. Most loads don’t draw a constant current.

How does high temperature affect relay operation?

Relationship with Temperature

Temperature changes affect the resistance of the copper wires used for coils by approximately 0.4% per °C This directly affects the Relay characteristics because the coil current, which generates the attractive force of an electromagnet, changes.

Can relays catch fire?

Switching arcs or Relay heating may result in fire or explosion. Wire the Relay correctly according to the Precautions for Correct Use when performing wiring or soldering. If the Relay is used with wiring or soldering that is defective, abnormal heating while power is supplied may result in burning.

What are the necessary precautions for high voltage testing?


  • All objects at ground potential must be placed away from all exposed high voltage points at a. minimum distance of 1 inch (25.4 mm) for every 7,500 Volts, e.g. 50 kV requires a spacing of at least. …
  • Allow a creepage distance of 1 inch (25.4 mm) for every 7,500 Volts for insulators placed in contact.

What are safety precautions in electrical installation?

Basic safety precautions

  1. avoid overloading sockets by providing enough socket-outlets.
  2. where possible switch off all appliances at the mains at the end of the working day.
  3. switch off and unplug equipment before you clean it or make adjustments.

What can cause a relay to stick on?

Excessive current flows to the contacts, and the resulting heat generated causes the contacts to melt, and then stick together inseparably. This occurs when the contacts circuit short-circuits or when a load to which excessive inrush current flows is switched.

What are the parameters of relay?

With that in mind, let’s look at some common relay specifications and the impact they have on switching systems.

  • Life Expectancy. …
  • Maximum Switching Volts. …
  • Cold Switching Voltage. …
  • Switch Current. …
  • Carry Current. …
  • Pulsed Carry Current. …
  • Power Rating. …
  • Minimum Switching Voltage.

What happens when a relay is energized?

When a relays coil is energized, current flow through the coil creates a magnetic field. Whether in a DC unit where the polarity is fixed, or in an AC unit where the polarity changes 120 times per second, the basic function remains the same: the magnetic coil attracts a ferrous plate, which is part of the armature.

How do you protect a relay coil?

To prevent damage you must connect a protection diode across the relay coil. Most relays are designed for PCB mounting but you can solder wires directly to the pins providing you take care to avoid melting the plastic case of the relay.
Coil resistance.

Relay coil current = supply voltage
coil resistance

How do you store relays?

Store relays in a humidity-controlled, shock- and vibration-free environment. Storage temperature range limits are –25°C to +85°C, however, when possible, relays should be stored in an ambient environment. 3. Do not expose relays to humid condition such that condensation may be formed due to sudden drop in temperature.

Can relays be mounted upside down?

Mounting the relay upside down means that both gravity and the return spring are working in a favorable direction to keep the coil core from making electrical contact. Also in the event of a spring failure the core will not move toward the contacts when not purposely engaged.

Does a relay need to be vertical?

Most relays should be mounted with their terminals pointed downward, unless it is a weatherproof, sealed unit, or a solid-state unit. 2) mechanical relays (virtually all automotive units) produce a small spark on contact, and that could ignite any fumes under hood if venting upward.

Can you mount a relay sideways?

Water runs into the relay box and into the relays, pooling inside and rusting them out. The relays are (obviously) not sealed. Some people mount the relay box sideways – this is also a bad idea. It really needs to be right side up to let any water drain properly and to keep the relays high and dry.

Can a solenoid be upside down?

Registered. mine are upside down.No problem.