high-voltage-full-range-current-limiting-fuse
This product is suitable for indoor AC 50Hz (60Hz) power systems with rated voltages of 8.3kV, 15.5kV, and 21.1kV. It serves as a protective element for overload and short circuit in power transformers and other electrical equipment.Primarily used in the oil of American-style transformer substations, this fuse can be equipped with a spring striker to provide a microswitch signal.
I. Basic Concept and Definition
A High-Voltage Full-Range Current-Limiting Fuse is a protection device designed for high-voltage distribution systems (typically 3.6kV to 40.5kV) capable of reliable operation across the entire fault current range-from the minimum fusing current to the maximum breaking current. It forcibly interrupts the current before a short-circuit current reaches its peak by utilizing the intense deionization effect of an arc within quartz sand filler, thereby limiting the passage of fault current.
2. The Structure of the Fuse
The series of fuses are mainly composed of sleeve, fuse element, spring contact, conductive ring, handle, flange,sealing ring, end cover and other parts. The fuse element and handle are installed in the sleeve. Its basic structure is shown in Figure 1:
Figure 1. Fuse Structure Composition Diagram
3. Fuses Are Dimensioned
The size of the fuse is shown in Figure 2; the size of the transformer oil tank opening is shown in Figure 3.
| rated voltage (kv) |
Rated current of fuse (A) |
A | B | C | D | E | Rated breaking current (kA) |
| 8.3 | 3~100 | 406 | 511 | 150 | 257 | 208 | 50 |
| 15.5 | 3~100 | 539 | 645 | 175 | 365 | 316 | |
| 21.1 | 3~80 | 614 | 720 | 175 | 440 | 391 | 40 |
Figure 2. The Shape and Size of the Fuse Base and Fuse Element
Figure 3. Transformer Tank Opening Size Diagram
4.Basic Technical Data
4.1 Insulation Level: The Insulation Level of the useis Shown in Table1
|
rated voltage
kV
|
Rated peak lightnin-g impulse withstandvoltage (positiveand negative poles) kV |
Rated 1 minutepower frequencywithstand voltage (effective value) |
Corona extinction voltage kV |
| 8.3 | 95 | 35 | 11 |
| 15.5 | 125 | 40 | 19 |
| 21.1 | 125 | 50 | 26 |
Break: the distance between the conductive parts of the contacts on the base of the fuse is isolated after the fuse element is
removed.
4.2 Arc Time-Current Characteristics and Current Limiting
Characteristics
When the ambient air temperature is 20℃, the arc front time current characteristic curve of the fuse is shown As Shown in Figure 4; the Current Limiting Characteristics Are Shown in Figure 5. The Allowable Deviation Is ±10℅.
Expected effective current value(A)
Figure4.Arc Time-Current Characteristic Curve
Expected effective current value(A)
Figure 5. Current Limiting Characteristic Curve
5. Selection of Fuse
The selection of the primary protection fuse of the transformer can be referred to Table 3; each manufacturer can use the fuse at reduced capacity according to the actual oil temperature around the fuse. When the temperature exceeds 40℃, the fuse should be reduced by 1% for every 1℃
increase in temperature.
| Transformer capacity(KA) | Primary voltage of tran-sformer (kV) | Rated current of fuse (A) |
| 160 | 8.3 | 31.5 |
| 200 | 40 | |
| 250 | 45/50 | |
| 315 | 55/63 | |
| 400 | 71/75 | |
| 500 | 80 | |
| 630 | 100 | |
| 160 | 15.5 | 20 |
| 200 | 25 | |
| 250 | 31.5 | |
| 315 | 40 | |
| 400 | 50 | |
| 500 | 63 | |
| 630 | 80 | |
| 800 | 100 | |
| 160 | 21.1 | 10 |
| 200 | 16 | |
| 250 | 20 | |
| 315 | 25 | |
| 400 | 31.5 | |
| 500 | 40 | |
| 630 | 50 | |
| 800 | 63 | |
| 1000 | 80 | |
| 1250 | 100 |
6. Installation of Fuse
6.1 The transformer box should have a round hole of ø103+1for placing the fuse, and four bolts of M10×45mm are welded around the round hole. The central hole is 116 away,as shown in Figure 3.
6.2 The fuse should be installed horizontally. The transformer enclosure should include an adjustable insulating bracket to ensure the fuse is level, which should then be securely fastened. The four ø14 holes of the fuse are connected to the oil tank's surface using M10 bolts, and the oil tank's seal is
ensured by a sealing ring.
6.3 Installation method of fuse
Note: The fuse is installed in place at the factory and does not need to be disassembled. You can refer to this method when maintaining and replacing it.
(1)When replacing the fuse, wear clean gloves and wipe the inner wall of the bushing and handle with clean cotton cloth.
(2). Install a conductive ring and spring contact at both ends of the fuse, connect to the handle and tighten.
(3) . Slowly push the installed fuse, handle, contact and assembly into the sleeve along the axis of the base. Do not tilt the handle to prevent the internal threads from loosening.
(4)If there is a micro motion signal, connect the micro motion switch joint to the screw rod at the top of the handle and tighten it.
7. Fuses Maintenance and Replacement
7.1 The fuse should be placed in a ventilated and dry warehouse. If the fuse is subjected to fall or other mechanical impact, check whether the fuse sleeve leaks before use, and whether the resistance value of the fuse element is within the standard range.
7.2 When the fuse element is in action, a new fuse element of the same model, specification and size should be replaced.
Do not replace it with other devices.
7.3 In a three-phase system,when one phase fuse is operated, according to IEC standards, all three phase fuses need to be replaced.
7.4 When replacing the fuse, be sure to replace it without power, and be careful when replacing it Be careful to prevent the fuse from falling or other mechanical impact.