Panel Indicator Lights: Basics, Colors, Selection
What is an Indicator Light?
The indicator light is a panel-mounted lamp assembly consisting of an indicator housing, an internal lamp, terminals, and a lens. The light source of indicator light is a high brightness pure color LED or incandescent bulb.
As the name implies, indicator lights reveal the status (ON or OFF) of an electrical apparatus in switchboards. In more sophisticated systems, the indicating lights may annunciate the cause of the current interruption, such as line-to-ground fault, overload, and overcurrent condition.
The customer usually selects the color of the lights for a particular indicating function. In selecting indicating lights, it is of paramount importance to know their voltage and resistance rating because these parameters establish the minimum current rating of the contact that controls the switching of the lights.
A motor’s fuses, circuit breakers, magnetic starters, and relays are all housed within a metallic cabinet—located on what is commonly known as a motor control center—on the front panel where the indicator lights and the start-stop pushbuttons are located.
Colors of Indicator Lights
Indicator lights include a colored lens such as red, green, blue, yellow/amber, clear, or white. These colored lenses symbolize the condition of the machine or equipment to which the lights are connected.
The IEC standard has adopted strict requirements concerning the application of indicator lamps. For example, IEC 60204-1 requires indicator lamps to be color-coded for universal application according to the format in the table:
Why LEDs are used in Indicator Lights?
LEDs are used in indicator lights due to the following reasons:
- LEDs are used when the heat generated by incandescent lamps would damage nearby equipment or interfere with a precision process. This is particularly advantageous when multiple lights are grouped.
- LEDs can operate at low temperatures which would cause incandescent lamps to fail since glass cracks during rapid cooling.
- LEDs consume 50 times less power than incandescent lamps, thereby reducing energy consumption.
- LEDs last 500 times longer than incandescent lamps. LEDs average a million hours (114 years) while incandescent lamps average 2000 hours.
- LEDs do not generally “blow out” unless subjected to a severe overvoltage. They exhibit a half-life type diminishment in brightness over time. After 50,000 hours (6 years) of use, LEDs will retain approximately half of their original intensity.
- LEDs have high visibility.
- LEDs require little or no maintenance because of their long life and high reliability.
Selection Parameters of an Indicator Light
When selecting an indicator light for a switchboard, the following parameters should be considered:
- Supply voltage
- Head type (Compact or modular)
- IP Rating
- Ambient and storage temperature
- Service life