FAQ
1: Could we become Shenle exclusive brand agent in our country?
We are keen to cooperate with our esteemed clients to develop the local market and build a mutually beneficial business relationship. If you would like to know more, please do not hesitate to contact us at [email protected].
2: Do you accept OEM/ODM for relay products?
Yes, we offer OEM/ODM services. If you have specific requirements, please do not hesitate to contact us. We would be happy to provide professional proposals and help design the perfect relay for you.
Service/Products
1: What certifications do you have for your products?
For different markets, we get our products approved by cURus, UL, CE, RoHS, TUV, EAC, UKCA, CSA, CQC, CP, and other standards organizations, to meet the needs of those markets.
2: Can I get a sample for reference?
We would provide some free samples for testing, and you would only need to pay the express shipping cost.
3: What is your warranty time of the products？
12 month in use and 18 month in stock.
4: Besides relay and socket, what accessories do you produce ?
To meet customer demands, we are also manufacturing protection modules, plastic clamps, metal clips, ID tags, and bus jumpers.
5: How long is the deliever time?
If there is stock we can send it right away.
6: What is your minimum order quantity?
It depends on the type of product you choose.
7: Where can I buy your products?
If you’re interested in our products, you can either buy them from our online store or get in touch with our sales department at [email protected].
8: What should we pay attention to in the selection of relay
For general electrical appliances, it’s important to think about the required volume, including cabinet space and circuit board layouts. Additionally, for small items such as toys and remote control devices, subminiature relays should be employed. Making sure you choose the right relay is critical for the proper functioning of your electrical system.
10: What are the applications of relay technology?
PLC relay technology has developed to the present and has been combined with computer technology to produce programmable controller technology. PLC for short. It is a kind of advanced equipment that directly uses microcomputer technology for automatic control.
It has the advantages of high reliability, strong anti-interference ability, complete functions, small size, flexibility and expandable, simple software, easy maintenance, beautiful appearance, and so on.
In the past, elevators controlled by relays had hundreds of contacts to control the elevator’s movement. If the contact connection is not good, it will cause failure and maintenance is quite troublesome. In a PLC controller, there are hundreds of solid state relays, and dozens of timers/counters, with power off memory function, input and output using photoelectric isolation, control system fault is only 10% of the relay control mode. Because of this, the relevant state departments clearly stipulated that since 1997, the new elevator shall not use a relay control elevator, using a PLC microcomputer control elevator.
It can be seen that relay technology is ubiquitous in daily life, and the close combination with the computer enhances its vitality so that the relay can better serve our life.
11: Why is the current transformer not allowed for secondary open-circuit operation?
When the secondary circuit of the CT in operation is open, the secondary current becomes zero and the degaussing effect disappears. At this time, all the primary current is used for excitation, which induces high electromotive force in the secondary winding, and its peak value can reach several thousand volts, which seriously threatens the safety of personnel and equipment.
In addition, the magnetization force generated by the primary winding makes the iron core suddenly saturated and the active power loss increases, which will cause the iron core to overheat and even burn the current transformer. Therefore, the secondary circuit of the CT is not allowed to be opened during operation.
12: Under what circumstances is the single-phase ground fault current greater than the three-phase short-circuit current?
A single-phase ground fault current is greater than a three-phase short-circuit current when the zero-sequence integrated impedance at the point of faulting is less than the positive-sequence integrated impedance. This phenomenon can be observed in a variety of electrical systems.
13: Why should generator excitation circuits be equipped with one-point and two-point ground protection?
Although the generator excitation circuit is grounded at one point, it will not form a fault current path, which will cause direct damage to the generator, but the possibility of second point grounding must be considered. Therefore, the single-point grounding protection sends a signal to strengthen inspection and monitoring.
When a two-point grounding fault occurs in the excitation circuit of the generator, the generator rotor will be burned out because the fault current flowing through the fault point is quite large. Due to short circuit in some windings, the current in the magnetic field windings will increase and may be burned out due to overheating. Winding short circuit, resulting in air gap magnetic flux out of balance, resulting in unit vibration. Steam turbines can also magnetize shafting and steam turbines.
Therefore, the two-point grounding protection should be adopted after the one-point grounding. In this way, when the two-point grounding occurs, the operation will be stopped after a delay.
14: Why should the generator be equipped with negative sequence current protection?
When an asymmetric short circuit or three-phase operation takes place in a power system, a negative sequence current is produced in the generator stator winding. This current generates a magnetic field that is twice the synchronous speed relative to the rotor and results in a frequency-doubled current flowing through different sections of the rotor. This high level of current can cause localized burn damage on certain parts of the rotor which could lead to guard ring heating and loosening, ultimately resulting in potential severe damage to the generator.
In order to avoid undesirable generator troubles, negative sequence current protection must be applied. Furthermore, the rotor shaft and stator base would experience the vibration of a frequency of 100Hz due to the acting alternating electromagnetic torque of 100Hz.
15: What is acceleration after reclosing?
In the event of a line fault, protective devices will initiate appropriate action to resolve the issue. A single auto-reclosing process may be able to restore the power supply.
Reclosing acceleration is a method of protection in which the circuit breaker is opened without any time delay when reclosing is in permanent failure. This non-selective action promotes safety for personnel, equipment, and structures.
16: What are the basic requirements for distance protection?
- When a direct short circuit occurs on the protected line, the measured impedance of the relay shall be proportional to the distance between the bus bar and the short circuit point
- When short-circuiting outside the forward zone, the action cannot be overridden
- There should be a clear direction
- It should still be able to work when it shorts out in the area due to a large transition resistance
- No action at a minimum load impedance
17: What are the maximum and minimum operating modes of the system?
In the calculation of the relay protection setting, the maximum and minimum operation modes of the power system must be considered.
Maximum working mode refers to the working mode in which the system equivalent impedance is minimum and the short circuit current through the protection device is maximum when the protected object is short-circuited.
Minimum operation mode refers to the operation mode in which the equivalent impedance of the system is maximum and the short circuit current through the protection device is minimum under the same short circuit condition.
18: What is the polarization of the distance relay?
In order to ensure the accuracy of the distance measure voltage, an additional AC quantity must be passed as a reference when forming the action amount of the distance relay. This nominal AC value is used for detecting Uph phase inversion when a fault occurs either inside or outside the protection zone and is often referred to as the polarization quantity of the distance relay.
19: What is the oscillation of the power system? What are the general reasons for the oscillation?
Systems or power plants running in parallel that lose synchronization constitute a phenomenon known as oscillation.
Various oscillations could be caused by a range of different factors, most of which involve the system’s stability being compromised over time as a fault is fixed. In systems that are linked more weakly, misoperation, loss of magnetization from generators, or other such issues can lead to an oscillation. All these scenarios should be taken into account when attempting to stabilize the system.
20: What is the difference between power system oscillation and short circuit?
In an oscillating system, the current and voltage values at all points will ebb and flow cyclically. However, the current and voltage values produced by a short circuit will be abrupt in comparison. This means that while oscillation produces changes in current and voltage that occur over time, a short circuit constitutes a much greater shift in the values of these parameters.
During oscillation, the phase angle between voltage and current fluctuates in response to changes in power angle; whereas during short-circuit conditions, the phase angle remains relatively constant.
22: What is the coil mark
The drive mode of the coil is shown below:
- Single stable type
- Double coil latching type
- Single coil latching type
- Polarity Non-polarity 4-terminal type
- 3-terminal type
Payment and Shipping
1: What's your payment method?
We usually accept T/T (100 %)
2: What are the ports of shipment?
Shanghai and Ningbo.
3: How many ways do you have for overseas delivery?
We provide numerous shipping methods including sea freight, air freight, land freight, and express. You can choose from popular carriers such as UPS, FedEx, DHL, and TNT.
4: As soon as possible is what I need, which delivery method should I choose?
Express is typically a faster shipping option, with most deliveries taking place within 7-14 days.
5: What is the most efficient method of delivery for a large order?
We recommend you select a reputable freight forwarder and allow them to handle your shipment. We will be in touch with them to coordinate delivery.
6: What types of currencies do you accept?
We only accept RMB, USD and EUR.
