Paghahambing ng Iba't Ibang 10kV Pole-Mounted Switches (Isolator Load Switch Circuit Breaker at Fuse)

2yrs + staff 1000+m² US$300,000,000+ China

Ano ang Pole-Mounted Switch?
Isang mekanikal na switching device na nakainstala sa mga outdoor utility poles sa 10kV overhead distribution lines, ginagamit sa suburban at rural distribution networks. Ito ay disenyo upang sirain, isara, at dalhin ang line load currents at fault currents.
Ang mga pole-mounted switches sa pangkalahatan ay binubuo ng isang switch body na may sensors + FTU (Feeder Terminal Unit). Ang mga switches na pinag-uusapan sa ibaba ay nasa kategorya ng pole-mounted disconnectors (isolators).

2. Klasipikasyon ng Pole-Mounted Switches
Maaaring ikasalamin ang mga pole-mounted switches mula sa maraming dimensyon. Ang mga pangunahing paraan ng klasipikasyon at katangian ay sumusunod:

Ayon sa Interrupting Capacity:

a. Pole-Mounted Disconnector (Isolator): Walang kakayahan sa pag-sirain ng arc; hindi makakapagsara o mag-interrupt ng normal na load current. May visible break (isolation gap). Ang pangunahing layunin nito ay i-isolate ang mga linya upang mapanatili ang kaligtasan sa panahon ng maintenance.
b. Pole-Mounted Load Switch: May basic na kakayahan sa pag-sirain ng arc; makakapagsara, dalhin, at mag-interrupt ng normal na load current (≤630A). Makakadala ngunit hindi makakapag-interrupt ng fault current.
c. Pole-Mounted Circuit Breaker: Malakas na kakayahan sa pag-sirain ng arc; makakapagsara, dalhin, at mag-interrupt ng normal na load current (≤630A) at fault current (≥20kA).
d. Pole-Mounted Fuse (Drop-Out Fuse): Ang pangunahing layunin ay mag-interrupt ng short-circuit current; ginagamit para sa proteksyon ng linya laban sa short-circuit.

3. Pole-Mounted Disconnector (Isolator)
Tinatawag din bilang "isolating knife switch," ito ay isang kontrol device na walang arc-extinguishing mechanism. Ang pangunahing layunin nito ay i-isolate ang power supply upang mapanatili ang ligtas na maintenance ng iba pang electrical equipment. Hindi pinapayagan ang operasyon sa ilalim ng load (mga low-power circuits lamang ang maaari nitong gawin/break sa ilalim ng tiyak na kondisyon). Isa ito sa pinaka-karaniwan at madalas na ginagamit na device sa high-voltage switching.

3.1 Pangunahing Layunin

De-energizing ng line equipment para sa maintenance, fault finding, cable testing, at reconfiguring ng operational modes.
Kapag binuksan, ito ay nag-iisolate ng equipment na ina-maintain mula sa live line, nagbibigay ng isang reliable na insulation gap at nagbibigay ng "visible, clear break indication" upang mapanatili ang kaligtasan ng mga tao.
Naglilingkod bilang isang demarcation switch sa pagitan ng overhead lines at user property, o sa pagitan ng cable lines at overhead lines.
Na-install sa isa o parehong bahagi ng tie load switch upang mapabilis ang fault finding, cable testing, at maintenance/replacement ng tie load switch.

3.2 Pangunahing Katangian

Advantages: Mababang cost, simple structure, matatag.
Limitations: Hindi maaaring gumana sa ilalim ng rated load/heavy load; hindi maaaring mag-interrupt o mag-make ng load current at short-circuit current.
Operating Procedure: Para sa energizing: "Close the isolator first, then close the circuit breaker/load switch." Para sa de-energizing: "Open the circuit breaker/load switch first, then open the isolator."
Special Permissible Conditions: Maaaring gawin/break ang magnetizing current ng no-load transformers (≤2A) at capacitive current ng no-load lines (≤5A).
Technical Parameters: Karaniwang peak withstand current (dynamic stability) ≤40kA (dapat ma-verify sa panahon ng selection). Mechanical operating life ay humigit-kumulang 2000 cycles.

4. Pole-Mounted Load Switch
Nakakargado ng simple na arc-extinguishing device, maaari itong gawin at mag-interrupt ng mga circuit sa ilalim ng load. Maaari itong mag-interrupt ng ilang load currents at overload currents ngunit hindi maaaring mag-interrupt ng short-circuit currents. Kailangan itong gamitin sa serye kasama ang high-voltage fuse (na nag-cut off ng short-circuit current). Ang functionality nito ay nasa pagitan ng isang isolator at circuit breaker. Ang pangunahing layunin nito ay line sectioning at fault isolation.

4.1 Common Types and Characteristics

Uri	Arc-Extinguishing Principle	Advantages	Applicable Scenarios
Gas-Production Load Switch	Solid gas-producing material generates gas under arc action, creating gas blast to extinguish arc.	Simple structure, low cost.	Scenarios with low operating frequency requirements.
Vacuum Load Switch	Vacuum arc extinction, often combined with SF₆ insulation.	Long life, maintenance-free, mechanical life ≥10,000 cycles.	Scenarios requiring frequent operation.
SF₆ Load Switch	SF₆ arc extinction + SF₆ insulation.	Excellent arc extinction/insulation performance, maintenance-free.	Scenarios requiring high reliability.

4.2 Mainstream Product Structural Features

Vacuum Load Switch: Three-phase common tank type, equipped with VSP5 electromagnetic/spring operating mechanism. Can have built-in current transformers (CTs) and isolation gaps. Supports cable/terminal outgoing lines. Can be mounted hanging or sitting.
SF₆ Load Switch: Three-phase common tank type. Can have built-in current transformers (CTs). Optional external isolation device. Supports cable/terminal outgoing lines. Can be mounted hanging or sitting.

5. Pole-Mounted Circuit Breaker
Isang switching device na may complete arc-extinguishing capability. Maaari itong pagsara, dalhin, at mag-interrupt ng normal circuit current, at maaari itong dalhin at mag-interrupt ng abnormal circuit currents (overload, short-circuit) sa loob ng tiyak na panahon. Ang kanyang function ay katumbas ng isang combination ng "fused switch + over/under thermal relay." Ang pole-mounted circuit breakers ay karaniwang tinatawag na "reclosers" o "auto-reclosers." Na-install sa mga poles, ito ang core equipment para sa proteksyon at control sa mga distribution network sections.

5.1 Core Uses

Sectionalizing, switching, control, and protection of distribution line segments; capable of actively interrupting and closing short-circuit currents.
Normally used to open/close lines; during faults, automatically or manually (via relay protection devices) switches out faulty lines.
Installed at responsibility demarcation points on 10kV overhead lines; can automatically clear single-phase earth faults and isolate short-circuit faults. A core device for distribution automation upgrades.

5.2 Classification and Mainstream Products
Classified by arc-extinguishing medium: Oil circuit breaker (largely obsolete), SF₆ circuit breaker, Vacuum circuit breaker (current mainstream).
Outdoor AC high-voltage intelligent vacuum circuit breakers are currently the preferred choice for distribution lines, featuring:

Functions: Fault detection, protection control, communication capabilities.
Operation Methods: Manual, electric, remote control, host computer remote operation.
Composition: Body + operating mechanism + controller (may include built-in isolator).
Optional Components: CT (Protection Current Transformer), ZCT (Zero-Sequence Current Transformer), PT (Voltage Transformer).

5.3 Vacuum Circuit Breaker Subtypes

SF₆ Insulated Vacuum Circuit Breaker: Vacuum arc extinction + SF₆ insulation. Three-phase common tank. Spring operating mechanism. Can have built-in CTs. Optional external isolation device. Hanging or sitting mounting.
Air Insulated Vacuum Circuit Breaker: Vacuum arc extinction + air insulation. Three-phase solid-pole type. Spring or permanent magnet operating mechanism. External CTs. Optional external isolation device. Sitting mounting.

6. Drop-Out Fuse
Commonly known as a "fuse cutout," it is the most commonly used short-circuit protection switch for branch lines and distribution transformers in 10kV distribution networks. It is economical, easy to operate, and suitable for outdoor environments. Widely used for protection and switching operations on 10kV lines and the primary side of distribution transformers.

6.1 Core Uses

Installed on 10kV distribution branch lines: Limits the scope of power outages. Provides an isolator function due to its visible break, creating a safe environment for maintenance.
Installed for distribution transformers: Serves as the main protection for transformers, safeguarding them against overload and short-circuit impacts.

6.2 Installation and Structure

Installation Location: Can be installed on the source side of a load switch (preferred when fuses don't need frequent replacement, allows the load switch to isolate voltage) or on the load side.
Core Components: Insulator, lower support base, lower moving contact, lower fixed contact, mounting plate, upper fixed contact, "duckbill" contact, upper moving contact, fuse tube.

7. Core Differences Between Pole-Mounted Switches
The key differences between various pole-mounted switches lie in three main dimensions: arc-extinguishing capability, types of interruptible current, and protection function. A detailed comparison is below:

Switch Type	Arc-Extinguishing Device	Interruptible Current Types	Carry Current Types	Protection Coordination Requirement	Core Purpose
Disconnector (Isolator)	None	Only system no-load current	Working current, short-circuit current (short time)	No protection coordination needed, used solely for isolation.	Safety isolation for maintenance, visible break.
Load Switch	Simple	Normal load current, overload current	Working current, short-circuit current (short time)	Requires series connection with fuse; fuse interrupts short-circuit current.	Line sectioning, normal load switching.
Circuit Breaker	Full	Normal load current, overload current, short-circuit current	Working current, short-circuit current (for specified time)	Requires coordination with relay protection device; protection issues trip command.	Fault clearance, comprehensive line protection.
Drop-Out Fuse	Simple	Short-circuit current, overload current	Working current (normal conditions)	Used alone, provides direct short-circuit/overload protection.	Short-circuit protection for branch lines & transformers.

Summary

Disconnector (Isolator): Only breaks no-load current; provides a "visible break point" for safe maintenance.
Load Switch: Breaks normal load current, not fault current; requires a fuse for fault protection.
Circuit Breaker: Breaks both normal load and fault currents; requires relay protection coordination; core device for distribution network protection.
Drop-Out Fuse: Specifically breaks short-circuit/overload currents; provides low-cost protection for branch lines and transformers.