What Is a Pilot Lamp?

There is often an indicator light on a key switch of a home light. The resistance of this kind of indicator light is extremely large, so that the current in the circuit is extremely small, so that the voltage of the electrical appliance at night cannot reach the rated voltage and cannot be lit. Generally, there is a capacitor in this indicator light, because a small The indicator light cannot tolerate a voltage of 220v.

Devices that use lights to monitor the operation or position of electrical circuits and electrical equipment. The indicator light is usually used to reflect the working status of the circuit (powered or unpowered), the working status of the electrical equipment (running, shutting down or testing), and the position status (closed or open).

The indicator light using incandescent lamp as the light source is composed of lamp holder, light bulb, lampshade and connecting wires. There are also light-emitting diodes as indicator lights, which are generally installed on the panel, panel, desk, cabinet panel of high and low voltage power distribution devices. , Some low-voltage electrical equipment, instrument panels or other more prominent locations. The indicator light reflecting the working status of the equipment, usually with a red light to indicate that it is in operation, a green light to indicate that it is out of service, and a milky white light that indicates that it is in a test state. Off means that the device is out of power; an indicator that reflects the working status of the circuit, usually the red light is on, and the green light is on. In order to avoid misjudgment, the condition of the light bulb or light-emitting diode should be checked frequently or regularly during operation.

The rated working voltage of the indicator light is 220, 110, 48, 36, 24, 12, 6, 3 V, etc. Due to the limitation of the current passed by the control circuit, and in order to extend the service life of the bulb, a current limiting resistor is often used in front of the bulb or two bulbs are used in series to reduce the working voltage. ^[1]

The number of dashboards installed in the cab depends on the design. It is used to indicate the technical conditions of lighting, light signals and working systems, and to issue alarm light signals for abnormal conditions.

As shown in the figure, a key switch of a home light often has an indicator light. In actual use, it is found that when the switch is closed, only the illumination lamp is illuminated; when the switch is off, the illumination lamp is extinguished, and the indicator light will emit a faint light, so that the position of the switch is displayed at night. According to the control characteristics of this key switch, the connection mode of the lighting lamp (A) and the indicator lamp (B) can be correctly indicated.

Crossroad lights,

The red, yellow and green lights are clearly distinguished.

Green light line,

Red light stops,

Stop and watch the lights.