FZRN21-12D/T125-31.5 AC high-voltage vacuum load switch fuse combinationDetailed product description：

1、 Scope of application
The FZRN21-12D/T125-31.5 type wide J internal AC high-voltage true narrow load switch fuse combination is suitable for use in power supply of two or three phase AC 50HZ, rated voltage 12KV. It is used for breaking load current, overload current and short-circuit current, and is particularly suitable for places without oiling, maintenance and frequent operation requirements. The load switch and combination device have obvious isolation faults, can be equipped with grounding knives and motor spring mechanisms with closing capabilities, and can achieve remote control.

2、 FZRN21-12D/T125-31.5 AC High Voltage Vacuum Load Switch Fuse Combination Model and Its Meaning



3、 Structural characteristics
3.1 Basic Structure
This combination electrical appliance is a three-phase linkage structure. (See Figure 1) It mainly consists of a frame (1), a vacuum arc extinguishing chamber (6), a fuse (3) acting as an isolation knife, a grounding knife (9), a trip rotating device (14), and a spring operating mechanism (17). The isolation knife, vacuum arc extinguishing chamber, and grounding knife are fixed to the frame through insulators. The spring operating mechanism is installed on the side panel of the frame.
3.2 Working principle
3.2.1 Operation of vacuum arc extinguishing chamber
The operation mode of the vacuum arc extinguishing chamber that constitutes the electrical appliance adopts an electric spring operating mechanism. You can also manually close the switch by turning the joystick clockwise, and open it manually or electrically.
3.2.2 Operation of opening and closing of isolation knife and grounding knife
There should be reliable interlocking between the vacuum arc chamber, isolation knife, and grounding knife of the composite electrical appliance. The isolation knife is linked with the grounding knife. When the isolation knife is opened to the isolation distance, the grounding knife starts to store energy and close or open. The grounding knife opens first, and the isolation knife closes later. Only when the vacuum arc extinguishing chamber is in the open state, can the isolation knife and grounding knife be operated; When the grounding switch is closed, the vacuum arc extinguishing chamber cannot be operated.
3.2.3 Fuse impact tripping and opening
When the short-circuit current or overload current flows through the main circuit of the composite electrical device in the closed position, at least one of the phase fuses of the fuse will melt, and the impactor will act, hitting the mechanical locking device of the composite electrical device, so that the vacuum arc extinguishing chamber can achieve reliable and fast opening under the action of the opening spring.
The structure and principle of the load switch are the same as the basic machine of the composite electrical device, and there is no fuse item (3) and trip mechanism item (14) in the instrument.

4、 FZRN21-12D/T125-31.5 AC High Voltage Vacuum Load Switch Fuse Combination Unit Appearance and Installation Dimensions



5、 Main technical parameters
1. Technical parameters of composite electrical appliances

serial number	Name	unit	parameter
one	rated voltage	KV	twelve
two	rated frequency	Hz	fifty
three	Maximum rated current of fuse	A	one hundred and twenty-five
four	Rated breaking and handover current	A	three thousand one hundred and fifty
five	The opening time of the switch triggered by the fuse	ms	40±5
six	Rated short-circuit breaking current (expected effective value)	KA	thirty-one point five
seven	Rated short-circuit ignition current (expected peak)	KA	fifty
eight	1-minute power frequency withstand voltage; Vacuum fracture phase, relative ground/isolated fracture	KA	42/48
nine	Lightning impulse withstand voltage: vacuum fracture Same, relative/isolated fracture surface	KV	75/85
ten	Rated short-circuit closing current (expected peak)	K	2~5

2. Main technical parameters of load switch

serial number	Name	unit	parameter
one	rated voltage	KV	twelve
two	rated frequency	Hz	fifty
three	rated current	A	six hundred and thirty
four	Rated Active load breaking current	A	six hundred and thirty
five	Rated closed-loop breaking current	A	six hundred and thirty
six	50% rated active load breaking current	A	thirty-one point five
seven	Rated cable charging breaking current	A	ten
eight	The breaking capacity of the rated no-load transformer	KVA	one thousand two hundred and fifty
nine	1-minute power frequency withstand voltage; Narrowly spaced fracture surfaces, relatively isolated fracture surfaces	KV	42/48
ten	Lightning impulse withstand voltage; Vacuum fracture Phase to phase, relative to ground/isolated fracture	KV	75/85
eleven	Rated short-time withstand current (thermal stability)	KNS	20/4
twelve	Rated peak withstand current (dynamic stability)	KA	fifty
thirteen	Rated short-circuit closing current	KA	fifty
fourteen	Rated current breaking times	time	ten thousand
fifteen	Mechanical lifespan (vacuum arc extinguishing chamber, isolation)	time	1 0000/20000
sixteen	Allowable wear thickness of vacuum arc extinguishing chamber contacts	mm	two
seventeen	Manual operating torque	N．m	four thousand and two hundred

3. Technical parameters for assembly and adjustment of vacuum arc extinguishing chamber

serial number	name	unit	unit
one	contact gap	mm	10±1
two	overrun	mm	4±0.5
three	Average closing speed	m/s	0.6±0.2
four	Average opening speed (before opening distance reaches 6mm)	m/s	1.1±O.2
five	The opening and closing phases of the two and three phase contacts are different	ms	≤2
six	Contact closing bounce time	ms	≤2
seven	Distance between charged bodies and relative ground	mm	≥125
eight	E、 Main circuit resistance between lower brackets	UQ	≤70

4. Technical parameters of fuses for combination electrical appliances

model	Rated voltage KV	Rated current of fuse A	Rated power on/off A	Rated current of melt A
SDLAJ	twelve	forty	thirty-one point five	6.3, 10, 16, 20, 25, 31.5, 40
SFLAJ		one hundred	forty	50, 63, 71, 80, 100
SKLAJ		one hundred and twenty-five	fifty	one hundred and twenty-five

6、 Ordering Notice
Users should indicate when placing an order:
a. Model, name, specification, quantity;
b. The name, specifications, and quantity of spare parts.
c. Operating mechanism model, operating voltage type and rated value.