Normally Open Contactor Symbol

Normally closed overload contacts.

Normally open contactor symbol.

Normally closed contact in the following illustration when the relay is de energized the example normally closed contacts are shown as closed and are not highlighted. Some of the most common and widely used symbols are given below 1. Rarely are these familiar examples good for learning but a 3 way switch is an excellent example of using normally open and normally closed switches. If the contact is normally open it would not allow any current to pass through it and hence there will be an open circuit at this contact.

Changeover contact this is the changeover contact of a relay that is closed or connected with one terminal known as normally closed terminal when the relay is deactivated the other terminal is open known as normally open terminal. The given symbol indicates a normally open contact. A complete path of current exists at this time and the light is on. In other words when voltage is applied to the relay contactor terminals this contact closes.

To avoid confusion it is common practice to draw one set of nc overload contacts and mark these contacts all overloads ols. Relays and contactors have two types of contacts each suited for different applications. Auxilliary contacts symbols for use in electrical pneumatic and hydraulic schematic diagrams. Most of the time a small voltage or current is used to switch other voltages or higher currents that may be electromechanical or fully electronic type.

We can tell this switch is a normally open no switch because it is drawn in an open position. Available in svg png jpg dxf dwg formats. Electric motor controls g. Now let s go through a real world example of normally open and normally closed contacts that we are all familiar with.

The relay are switching devices activated by signals. The contacts open when the relay activates to break the circuit. Normally open no contacts allow current when the relay or contactor is energized. It is the contact of relay that is in closed position when there is no power supplied.

The lamp will energize only if someone presses the switch holding its normally open contacts in the closed position normally open switch contacts are sometimes referred to in the electrical industry as form a contacts. Anywhere from 1 to 3 nc overload contacts are shown between the starter and l2 in all line diagrams. When the relay is energized the contacts open turning the light off.