2. Normally open contact A normally open (N.O.) contact is a contact that is open or in a non-conductive state when it, or the device operating it, is in a de-energized or relaxed state. An example of a normally open contact usage is the co... [read more]

1. Normally closed contacts Light switch with a normally open contact A normally closed (N.C.) contact is a contact that is closed or in a conductive state when it, or the device operating it, is in a de-energized or relaxed state.... [read more]

An electrical contact is an electrical circuit component found in electrical switches, relays and breakers. It is composed of two pieces of electrically conductive metal that pass electrical current or insulate when the gap between them is ... [read more]

A mercury switch (also known as a mercury tilt switch) is a switch which opens and closes an electrical circuit through a small amount of liquid mercury.... [read more]

Since mercury is a poisonous heavy metal, devices containing mercury switches must be treated as hazardous waste for disposal. Because it is now RoHS restricted, it has been eliminated in most modern applications.... [read more]

Uses of Mercury Switch (Part 2) 5. Thermostats Mercury switches were commonly used in bimetal thermostats. The weight of the movable mercury drop provided some hysteresis by moving the bimetal spring slightly beyond the point it would no... [read more]

Uses of Mercury Switch (Part 1) 1. Roll sensing Tilt switches may be used for a rollover or tip over warning for construction equipment and lift vehicles operating in rugged off-highway terrain. There are several non-mercury types but few a... [read more]

Disadvantages when compared with other types include: Mercury switches have a relatively slow operating rate due to the inertia of the mercury drop, so they are not used when many operating cycles are required per second.... [read more]

Advantages of the mercury switch over other types are that the contacts are enclosed, so oxidation of the contact points is unlikely. In hazardous locations, interrupting the circuit will not emit a spark that can ignite flammable gasses.... [read more]

Mercury switches have one or more sets of electrical contacts in a sealed glass envelope which contains a bead of mercury.... [read more]