Baoding Weifan Electricity Technology Co., LTD.

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Baoding Weifan Electricity Technology Co., LTD.

Electric Power product manufacturer and overall supply chain services An electric power product manufacturer from China Electric Valley.

Founded in 2012, the company has been committed to the supply chain services of electric power products, providing overall supply chain services including transformers, neutral point grounding equipment, power meters, cables, insulation products, experimental equipment, and power transmission and distribution design, supply, and installation.

16/10/2024

DISCHARGING A CAPACITOR BANK

The dangerous high voltage due to the energy stored in a capacitor bank needs to be discharged in a controlled way. Safety regulations require that dangerously high voltages must be below a safe voltage level within a certain time 8normally 1 or 2 minutes). A discharge resistor switched across the capacitor bank after the system is turned off, is a reliable and cost-effective way of ensuring this.

ENERGIZING A TRANSFORMER

When a transformer is energized for the first time, a magnetic field must be first be established in the core. For the first few cycles, the magnetizing current is limited only by the ohmic resistance and air-cored reactance of the primary winding. As soon as the magnetic field is established. The current decreases to that of the iron-cored reactance. To prevent such high inrush currents, “pre-magnetizing” resistors are inserted in the primary circuit and these are by-passed once the transformer is magnetized. Pre-magnetizing is essential when the energy grid is weak and utility regulations forbid high current peaks taken from supply.

18/09/2024

STARTING

Starter resistors are used for wound-rotor induction motors or for squirrel-cage stator motors (normally one step) to limit peak current during starting. The resistor topology can be a three-phase resistor with fixed ohmic value or a multiple three-phase topology with different resistor-value steps.

BRAKING

Brake resistors are used in many Traction, Marine (e.g thrusters and winches) and industrial Drive applications. During braking, power is generated via the electronic inverter and must be dissipated (if not absorbed by the supply) in order to prevent damage to the power electronics. Brake resistors ratings range from a few hundred watts up to several MW and the demands on these resistors are highly application dependent.

17/09/2024

LINE TEST RESISTORS

Line test resistors for railway applications are used to detect fault conditions on overhead lines (catenaries) before switching on the power. The line-test resistor is switched to the line and if no fault current is detected it is deemed safe to close the HSCB (High-Speed Circuit-Breaker) as HSCB lifetime is inversely proportional to the number of fault clearances. Indeed, it may be required that such a test (with fault conditions) be repeated several times in a row and these resistors can help to locate the faults when several short line-test are applied.

TRAIN BRAKING RESISTORS

Braking a train is always done by electric resistors. Mechanical brakes wear out too quickly and require expensive maintenance. During braking, the kinetic energy of the train is transformed into electric energy and if possible, fed back to overhead line but this can only be done if another train is connected to the same overhead line and can use the energy. If this is not possible, then the energy must be dissipated as heat in onboard resistors. There are three possible locations for brake resistors:
On the roof of the train where the hot air is released upwards.
On the chassis of the train where the hot air is released to the side.
Inside the vehicle in special compartments.
All locations may use natural convection or forced-air cooling.

16/09/2024

Load Banks are used for testing equipment such as (emergency) generators and UPS systems or also dummy loads to maintain the generator at the minimum temperature. Load banks are offered from a few kW up to 10MW and from working voltages of a few hundred volts up to 36kV. Load banks are built from several steel-grid building-blocks making it easy to split up the load bank into (many) smaller loads. Load banks are made for both indoor and outdoor use in IP classes up to IP23. Higher IP ratings are problematic as it becomes more difficult to dissipate heat.

Crowbar resistors are used to suppress transient or short-duration voltage peaks in traction and industrial applications. Crowbar resistors are designed to handle high power loads for limited periods.

14/09/2024

Neutral-earthing resistors (NERs) are used to ground the neutral point in a (medium) voltage grid. The resistors limit the fault current in the case of a phase-to-ground short circuit. A NER limits damage, resulting in shorter and fewer downtimes. The main advantages of NERs over alternative grounding methods is that they limit fault currents, allow simple fault-detection and do not produce over-voltages.

Our NERs are Achilles REPRO certified, so they can be installed at facilities of of the main energy companies of Southern Europe and LATAM.

NERs are selected based on voltage, fault current and duration-of-fault-current. Normally the resistors is chosen based on the energy [E] in joules that can be absorbed by the elements without exceeding the maximum element temperature, energy being power integrated over time, where typical fault-times last 10 to 30 seconds. The power will vary slightly, depending on the resistance’s temperature coefficient. At the start of the fault, the current will be higher due to the resistor’s lower ohmic value but as the element heat up, the fault current will drop.

10/09/2024

Corrugated Resistor

It uses a ceramic tube as the skeleton, and the alloy resistance wire is evenly wound on the skeleton. The surface is coated with high-temperature resistant insulating paint. It is easy to install and has good heat dissipation capacity. It can be used in electrical circuits such as inverter braking, servo systems, and power supplies.

Address

Baoding
071000

Website

https://mfrdo.com/about/

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