(1)Very Low Frequency Method
As we know that the cable capacity is large. After the power frequency test, the transformer capacity changes. It is necessary to increase the test power supply with a large capacity to fundamentally ensure that the cable can provide reactive power during operation. However, this method cannot be used in the field. The low frequency is the main test power source. However, the ultra-low frequency method has a relatively poor effect on the insulation defects of the cross-linked polyethylene cable and accessories detected. Therefore, the frequency of the over-frequency method applied to the voltage cable at this stage is relatively high.
(2) Oscillating Voltage Method
When the cable is subjected to DC shock, the resistance and inductance are discharged after a certain voltage, and then the damped vibration voltage is formed. The damped vibration voltage can be used to detect defects in the cable insulation and accessories. This is still very important in the DC withstand voltage test. The effect, but the essence is still mainly manifested in two aspects: on the one hand, the oscillating voltage is weakened, which cannot fundamentally satisfy the cable, on the other hand, the high-frequency voltage will cause varying degrees of damage to the cable.
(3)Resonance withstand voltage method
The resonance withstand voltage method mainly refers to changing the cable and frequency in the experimental circuit to make the circuit as a whole in a resonance state. The resonance withstand voltage method can meet the test requirements of high voltage and large current. In addition, from the point of view of the adjustment method of the resonance withstand voltage method, it can be divided into two types: inductance and frequency modulation. From the use method of the resonance withstand voltage method, it can be divided into two types: series resonance and parallel resonance.
1. Inductive resonance withstand voltage
After adjusting the power inductance of the reactor and the basic capacity of the cable, resonance will occur at 50HZ, which meets the basic needs of the entire test
2. FM resonance withstand voltage
When changing the output frequency of the power supply in the test, the fixed inductance in the circuit and the corresponding test piece fundamentally meet the basic requirements of resonance and the basic requirements of the entire test.
3. Series resonance method
During the test, the current of the transformer must meet the requirements of the test as a whole, but when the voltage does not reach the test voltage, a reactor or a series of test pieces must be selected for the test. When the circuit is in resonance, the test product appears to be a multiple of the corresponding circuit quality factor, and the output voltage of the transformer changes. Before the power supply capacity is satisfied, the effective power in the circuit will be lost.
4. Parallel resonance method
In the test, when the voltage of the transformer meets the test requirements and the current does not meet the requirements, the reactor and the test product are connected in parallel to meet the circuit parameters required for resonance in the test to promote the active development of the test. At the same time, the parallel resonance method and reactor are selected. The basic inductive current compensates the capacitive current of the test product.
1.Use Proper Power Cord
Only use the power wire supplied by the product or meet the specification of this produce.
2.Connect and Disconnect Correctly
When the test wire is connected to the live terminal, please do not connect or disconnect the test wire.
The product is grounded through the power wire; besides, the ground pole of the shell must be grounded. To prevent electric shock, the grounding conductor must be connected to the ground.
Make sure the product has been grounded correctly before connecting with the input/output port.
4.Pay Attention to the Ratings of All Terminals
To prevent the fire hazard or electric shock, please be care of all ratings and labels/marks of this product. Before connecting, please read the instruction manual to acquire information about the ratings.
5.Do Not Operate without Covers
Do not operate this product when covers or panels removed.
6.Use Proper Fuse
Only use the fuse with type and rating specified for the product.
7.Avoid Touching Bare Circuit and Charged Metal
Do not touch the bare connection points and parts of energized equipment.
8.Do Not Operate with Suspicious Failures
If you encounter operating failure, do not continue. Please contact with our maintenance staff.
!Do Not Operate in Wet/Damp Conditions.
!Do Not Operate in Explosive Atmospheres.
!Ensure Product Surfaces Clean and Dry.