Overview
The JN22B-40.5/31.5 is an indoor high voltage earthing switch (grounding switch) developed from the original JN15 type for 40.5 kV (rated voltage 35 kV), 50 Hz three-phase systems. It matches KYN□-40.5 and other types of metal-enclosed switchgear as the earthing-protection element, and its performance complies with IEC 129 and IEC 62271-102.
Under voltage but without load it bonds the de-energised circuit to earth for maintenance safety, and can close onto a short-circuit current. It is rated 31.5 kA for 4 s short-time withstand current with 80 kA peak and short-circuit making current, and is supplied with phase-center distances of 280, 300, 350, 360 and 400 mm to suit different cubicles.
Model Designation
The type is designated JN 22B – 40.5 / 31.5 – □ and decoded as follows:
- JN — indoor earthing switch
- 22B — design number
- 40.5 — maximum (rated) voltage in kV
- 31.5 — 4 s thermal-stability (short-time withstand) current in kA
- □ — central distance between poles in mm
Construction and Operation
The JN22B-40.5 carries its three earth knives on support insulators above a common frame, driven through a transmission shaft by a manual operating mechanism so that all three poles make or break the earth connection together. The knives engage silver-plated static contacts sized to close reliably onto a short-circuit current, and the mechanism can be interlocked with the associated switchgear or cubicle door to prevent mal-operation. The compact three-pole assembly mounts inside 40.5 kV metal-enclosed switchgear, and where the phase-center distance is below 360 mm an insulation board is added between the phases; the frame is bonded to the earth network to complete the protective path.
Technical Parameters
Rated Parameters
| Item | Unit | Data |
|---|---|---|
| Rated voltage | kV | 35 |
| Maximum (rated) voltage | kV | 40.5 |
| Rated frequency | Hz | 50 |
| Rated short-time withstand current | kA | 31.5 |
| Rated short-circuit duration | s | 4 |
| Rated peak withstand current | kA | 80 |
| Rated short-circuit making current | kA | 80 |
| Phase-center (between-pole) distance | mm | 280 / 300 / 350 / 360 / 400 |
| 1 min power-frequency withstand voltage (phase to earth) | kV | 95 |
| Lightning impulse withstand voltage (phase to earth) | kV | 185 |
| Standard | — | IEC 129; IEC 62271-102 |
Operating Conditions
- Ambient temperature: −10 to +40℃
- Altitude: not above 1000 m
- Relative humidity: daily average not above 95%, monthly average not above 90%
- Seismic: intensity not above 8 degrees
- Site: free from corrosive or flammable gas and no frequently intense vibration
Installation & Wiring
Installation and Mounting
Fix the earthing-switch frame to the cubicle mounting plane through the 20 × 9 × 19 oval holes at the selected phase-center distance, keeping the earth knives and static contacts clear of obstructions. Couple the three poles to the manual operating mechanism through the transmission shaft, then verify simultaneous and full contact seating of all three poles, correct interlock action and bonding of the frame to the earth network before energising.
Outline & Mounting Dimensions
| Model | E (mm) | G (mm) | L (mm) | D (mm) |
|---|---|---|---|---|
| JN22B-40.5/31.5-280 | 280 | 290 | 1010 | 656 |
| JN22B-40.5/31.5-300 | 300 | 340 | 1100 | 696 |
| JN22B-40.5/31.5-350 | 350 | 340 | 1200 | 796 |
| JN22B-40.5/31.5-360 | 360 | 320 | 1200 | 816 |
| JN22B-40.5/31.5-400 | 400 | 340 | 1300 | 896 |
E is the phase-center distance; mounting holes 20 × 9 × 19. Where the phase-center distance is below 360 mm an insulation board is added between the phases.
Selection & FAQs
Ordering Information
- When ordering, state the full model, rated voltage, rated short-time withstand current and phase-center distance, together with any accessory requirement.
- Select the phase-center distance (280 / 300 / 350 / 360 / 400 mm) to match the cubicle busbar layout; below 360 mm an inter-phase insulation board is fitted.
- Any special requirement is to be settled between the user and the manufacturer.
Frequently Asked Questions
Q1: What does the type designation JN22B-40.5/31.5 mean?
JN is the indoor earthing switch and 22B the design number; 40.5 is the maximum voltage in kV, 31.5 the 4 s short-time withstand current in kA, and the trailing figure the central distance between poles in mm.
Q2: What is the JN22B-40.5 used for?
It is an indoor medium-voltage earthing switch developed from the JN15 type, matching KYN□-40.5 and other metal-enclosed switchgear as the earthing-protection element in 40.5 kV, 50 Hz systems.
Q3: What are the rated values?
Rated voltage 35 kV (maximum 40.5 kV) at 50 Hz, rated short-time withstand current 31.5 kA for 4 s, rated peak withstand current 80 kA and rated short-circuit making current 80 kA.
Q4: Which standards does it comply with?
Its performance complies with IEC 129 and IEC 62271-102.
Q5: What phase-center distances are available?
Five types — 280, 300, 350, 360 and 400 mm, with overall length L of 1010, 1100, 1200, 1200 and 1300 mm respectively; below 360 mm an insulation board is added between the phases.
Q6: Where can I see related products?
See the high voltage earthing switches range for related models.