FLN36-12 Indoor High-Voltage SF6 Load Break Switch Thomas Electric

Product Overview

The FLN36-12 indoor high-voltage SF6 load break switch is a three-phase switching device for 10/12 kV, 50 Hz distribution systems, developed from absorbed foreign technology and built to local operating requirements. Full type tests confirm conformity with GB 3804 for 3-63 kV AC load break switches, GB 16926 for load break switch-fuse combination units, and IEC 60265 and IEC 60420. The series covers the plain load break switch, the FLRN36-12 load break switch-fuse combination unit, and cable-head versions for cable branch boxes, so the same frame serves switching, isolation and earthing duties in urban networks, industrial plants, high-rise buildings, residential districts and package substations.

Product Display

FLN36-12 Indoor High-Voltage SF6 Load Break Switch - display

FLN36-12 Indoor High-Voltage SF6 Load Break Switch - poster_display

Model Designation

FLN36-12 Indoor High-Voltage SF6 Load Break Switch - model

Model format: FLN36-12(24)/(D)T 630-20 (load break switch) and FLRN36-12 (switch-fuse combination unit)

FL: SF6 load break switch; N: indoor type; 36: design sequence number
12 (24): rated voltage, kV
D: with earthing switch; T: spring operating mechanism
630: rated current, A; 20: rated short-time withstand current, kA
R after FL: fuse combination; trailing figures give fuse rated current and prospective short-circuit breaking current
Other voltage, current and fuse combinations are available on request

Service Conditions

Ambient temperature: +40 °C maximum, -25 °C minimum
Altitude: not more than 1000 m
Relative humidity: daily average not more than 95%, monthly average not more than 90%
Seismic intensity: not more than 8 degrees
Site condition: no fire, explosion, chemical corrosion or severe vibration
Pollution level: II

Construction

The three poles are carried on a steel frame with epoxy insulator columns and house a sealed SF6 interrupter with on-off-earth three-position action and reliable interlocking. The design gives high break-point insulation and a large creepage distance, with a grading shield covering the outgoing terminals.

Dynamic and static seals keep the gas chamber tight while a clearly visible pressure gauge allows the sealed system to be monitored in service. Versions for cable heads accept touch-safe elbow connectors on the outgoing terminals for use in cable branch and ring main units.

Technical Data

No.	Item	Unit	FLN36-12	FLRN36-12
1	Rated voltage / highest voltage	kV	10/12	10/12
2	Rated current	A	630	125 (fuse)
3	Rated short-time withstand current (3 s)	kA	20	—
4	Rated peak withstand and short-circuit making current	kA	50	80
5	Rated short-circuit breaking current	kA	—	31.5
6	Rated transfer current	A	—	2000
7	Power-frequency / lightning impulse withstand voltage	kV	42/75	42/75
8	Mechanical life	operations	3000	3000
9	Rated SF6 gas pressure	MPa	0.045	0.045

Selection note: if the application data go beyond the listed scopes, such as sites above 1000 m altitude, 24 kV insulation levels or non-standard fuse ratings, they may be subject to agreement between manufacturer and purchaser. Final parameters are subject to nameplate data and approved specifications.

Standards

Full type tests confirm conformity with GB 3804 for 3-63 kV AC high-voltage load break switches, GB 16926 for high-voltage load break switch-fuse combination units, IEC 60265 for indoor high-voltage switch-disconnectors, fuses and switch-fuse combinations, and IEC 60420 for high-voltage alternating-current switch-fuse combinations.

Technical note: final parameters are subject to nameplate data and approved specifications.

Installation & Dimensions

Installation Diagram

FLN36-12 Indoor High-Voltage SF6 Load Break Switch - installation

The frame is fixed level inside the switchgear cubicle or ring main unit, and the earthing terminal is bonded to the earth grid with a dedicated conductor. Verify the on-off-earth three-position indication and the interlocking action, confirm that the spring mechanism charges and releases smoothly, and check that the SF6 pressure gauge reads within the specified range before the power-frequency withstand test on the main circuit.

Dimension	Value (mm)
Single pole height / width / depth	360 / 192 / 230
Three-pole width, 125 A / 200 A / 630 A	694 / 714 / 734
Fixing centres, 125 A / 200 A / 630 A	240 / 305 / 345
Front flange holes	4 × Ø10
Side flange holes	Ø8.5
Cubicle depth with spring mechanism box	325

Safety notice: installation, operation and maintenance must be performed by qualified professionals. Before maintenance, move the switch to the open position, confirm the indicated disconnection state, close the earthing switch and verify absence of voltage. Do not operate the switch when the SF6 gas pressure falls below the specified value, and never use the load break switch to interrupt short-circuit current.

FAQs

It is an indoor three-phase load break switch for 10/12 kV, 50 Hz systems, used to make and break load current and to isolate circuits for maintenance in industrial plants, high-rise buildings, residential distribution rooms and package substations. Short-circuit protection is provided by back-up fuses or upstream devices.

FLN36-12 is the load break switch alone, rated 630 A with a 20 kA short-time withstand current. FLRN36-12 is the load break switch-fuse combination unit: the same switching body is paired with back-up fuses, typically 125 A, that break short-circuit currents up to 31.5 kA, with a rated transfer current of 2000 A and a rated short-circuit making current of 80 kA.

FL is the SF6 load break switch, N indoor type, 36 the design sequence number, 12 (or 24) the rated voltage in kV, D the earthing switch, T the spring operating mechanism, 630 the rated current in A and 20 the rated short-time withstand current in kA. In the combination unit the letter R after FL denotes the fuse combination, and the trailing figures give the fuse rated current and the prospective short-circuit breaking current.

The sealed SF6 interrupter gives on-off-earth three-position action with reliable interlocking, so one device switches, isolates and earths the feeder. The earthing position provides a solidly earthed, visibly indicated safe state for maintenance, and the clearly visible pressure gauge allows the sealed gas system to be monitored in service.

Cable-head versions accept touch-safe elbow connectors on the outgoing terminals for use in cable branch and ring main units, while plain versions use bar or busbar connections. A grading shield covers the outgoing terminals, and the design gives high break-point insulation and a large creepage distance.

Full type tests confirm conformity with GB 3804 for 3-63 kV AC load break switches, GB 16926 for load break switch-fuse combination units, and IEC 60265 and IEC 60420. Sites above 1000 m altitude, 24 kV insulation levels or non-standard fuse ratings are subject to agreement between manufacturer and purchaser.

FLN36-12 Indoor High-Voltage SF6 Load Break Switch