Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Human body infrared detector circuit

Differences between Overcurrent Relays and Directional Overcurrent RelaysCurrent relays and directional overcurrent relays are both devices used to protect power systems, but they have different functions and application scenarios.Current RelayA current relay is a protective device mainly used to detect whether the current in the circuit exceeds the preset rated value. When the current in the circuit exceeds the set value, the current relay quickly cuts off the circuit or sends an alarm signal t

An AC motor (AC Motor) is designed to work with alternating current (AC) power, and its internal structure and operating principles differ from those of a DC motor (DC Motor). As such, directly connecting an AC motor to a DC power source will not allow it to function normally. However, theoretically, there are some special methods to make an AC motor self-excite on a DC power supply, though these methods are uncommon and not recommended for practical use, as they could result in motor damage or

Fuses may blow even in the absence of an apparent load, and this is usually caused by one or more of the following reasons: Short Circuit: This is one of the most common reasons. When the positive and negative terminals in a circuit come into direct contact, it creates a massive current that causes the fuse to immediately melt. Short circuits can be caused by worn-out wiring, dampness, or foreign objects intruding. Fuse Quality Issue: Using low-quality or inappropriate fuses can also lead to fre

I. Causes of overvoltage faults in frequency convertersOvervoltage at power inputGrid fluctuationThe grid voltage itself may fluctuate. For example, during the low-load period of the grid, due to the reduction of load, the grid voltage may increase. If the input voltage allowable range of the frequency converter is limited, when the grid voltage exceeds this range, it will cause an overvoltage fault in the frequency converter. Generally, the grid voltage may fluctuate within the range of ±10% -

Electrical equipment failures may cause the following two main dangers:I. Danger of electric shockDirect contact electric shockWhen an electrical equipment fails, such as when insulation is damaged and wires are exposed, if a person accidentally touches the live part, direct contact electric shock will occur. For example, if the insulation of a motor is punctured and the motor casing is live, and an operator touches the casing, the current will flow through the human body into the ground, causin

The shaded pole AC motor is a single-phase AC motor. It has characteristics such as simple structure and low cost, and is widely used in some small electrical appliances.Structural principleStator structureThe stator core is generally salient pole type and has multiple magnetic poles. On a part of each magnetic pole, there will be a short-circuit ring. This short-circuit ring is like "covering" a part of the magnetic pole, so it is called a shaded pole.For example, in a two-pole shaded pole moto

The most effective way to use large capacitors mainly depends on the specific application scenario. Here are some common application scenarios and their usage methods: Energy Storage: Large capacitors can be used for energy storage, especially in situations where a large amount of energy needs to be released quickly. For example, in audio systems, large capacitors store energy for the amplifier to use on demand. Uninterruptible Power Supply (UPS)- In a UPS, large capacitors can serve as a backup

When an alternating current passes through a coil, the following situations occur:I. Electromagnetic effects1. Generation of a magnetic fieldWhen an alternating current passes through a coil, an alternating magnetic field is generated around the coil. The intensity of this magnetic field changes with the change of current.For example, in an electromagnet, when an alternating current passes through a coil, a magnetic field that attracts ferromagnetic objects is generated. The direction and intens

There are mainly the following reasons why the starting relay does not jump or spark due to a jumper wire:I. Relay design and functionInternal structure designThe starting relay usually has a specific internal structure, including parts such as an electromagnetic coil and contacts. When the electromagnetic coil is energized, it generates a magnetic field that attracts the contacts to close or open, thereby realizing the on-off control of the circuit.For example, the contacts of the relay are usu