Scéim Impleachta do Thógáil Folaíochtaitheoirí nó Iontúir Vóltáis i Ringe Príomhuithe Chosainta Áirithe
De réir cineál na gaisceáin, is féidir ring main units (RMUs) a chategoriseadh mar gaisceáin-gaisithe nó gaisceáin-aer. Cuirtear componaidí an chiorcail phríomha i bpuisín meála dúnta atá lán de ghás íseal-bhrú (go príomha SF₆ nó gaiseanna mírthe) mar mhéadán gaiscthe, ag úsáid teirne cábail do théirnín isteach agus amach. Mar gheall ar an gaisceacht shonrach, an méide uafásach, agus an dianchumraíocht, tá siad in úsáid go forleathan i stáisiúin riaracháin 10kV tuaithe agus stáisiúin trasfhoirmiúcháin réamhghoillithe. In ainneoin sin, díríonn a n-ghaisceacht lán agus a n-meide uafásach orthu i gcúrsaí roinnt réimsí réamhscoite.
1 Céimeanna le RMUs Gaisceáilte
Léaráid 1 léiríonn dianchumraíocht réamhscoite stáisiún riaracháin, áit a bhfuil an seórdhathúil-fús cumhachtach ag iarraidh scúthú folgaid, agus an caibéal trasfholtáin (VT) ag iarraidh dhá VT trasfholtáin cast resin 10/0.1/0.22kV. Má roghnaíonn tionscadail RMUs gaisceáilte cosúil leis an RM6 ó Schneider nó an Safenng ó ABB, ní féidir leis an dianchumraíocht bheith sásaithe go hiomlán.
1.1 An Deacracht Scúthaí Folgaid a Chur I Stádas Fús-Cabhail
Do théirnín isteach/amach fús-cabhail, cuireann an dá brand spás cabhail leor le Type-C bushings (IEC 60137-compliant), ag ceadú T-type accessories cabhail agus scúthaí folgaid plug-in. I stádas fús-cabhail:
- Safenng: Fúsaí curtha ar an urlár (Léaráid 2) a choinneáil spás cabhail, ag ceadú scúthaí folgaid plug-in a chur.
- RM6: Fúsaí curtha suas (Léaráid 3) a dhéanamh brú ar spás cabhail, le Type-A bushings a dhéanamh teorainn ar accessories elbow/straight. Níl spás ann do scúthaí folgaid plug-in, agus níl scúthaí folgaid ar an margadh atá cothrom le dhúshlán elbow/straight.
1.2 An Deacracht VTs a Chur I Caibéal VT
Caibéal VT réamhscoite ag iarraidh trí aonad fús airde voltaí agus dhá VT aonphhas V-connected (dual-winding, 10/0.1kV le haghaidh measúnach, 10/0.22kV le haghaidh soláthar; ≥1000VA output deara). RMUs aer-chosanta (mar shampla, Schneider SM6) a chuir spás leor (500×840×950mm). In ainneoin sin, RMUs gaisceáilte a chuir spás cabhail uafásach (~400×350×700mm), neamhdhleathach do accessories cabhail, cables ceangail, fúsaí bosca, VTs, nó 125mm spás idir phásáil/ground.
Ginearálta, cuireann déantóirí caibéal folamh taobh le caibéal fús-cabhail chun VTs agus fúsaí a chur, ag ceangal leo trí cables. In ainneoin sin, díríonn sé:
- Sábháilteacht le linn oibriú VT mar gheall ar absánta interlocks meicniúla.
- Meide uafásach agus gaolachas stáisiúin tuaithe.
2 Réitigh Scúthaí Folgaid a Chur
2.1 Omitting Arresters
DL/T 620-1997 Overvoltage Protection and Insulation Coordination for AC Electrical Installations mandates surge arresters for cables >50m connected to overhead lines. For ≤50m cables, arresters may be installed at one end only. However, the standard does not explicitly require arresters on plug-in cable heads of 10kV gas-insulated RMUs.
Modern urban buildings feature extensive lightning protection networks, reducing lightning strike risks. Overhead cable connections are rare in cities, making direct lightning surges to cable cores unlikely. International practices (e.g., T-type arrester accessories) are often omitted in urban areas. Gas-insulated RMUs in Zhejiang Province operate reliably for years without arresters. Therefore, arresters can be omitted for urban gas-insulated RMU substations.
2.2 Arrester Selection Criteria
For suburban/rural grids with overhead-connected cables >50m, arresters must be installed. For load switch-fuse units, specify horizontally arranged fuses to reserve arrester space, avoiding retrofitting issues.
3 Voltage Transformer Installation Solutions
VT cabinet miniaturization requires resolving electrical insulation and space constraints.
3.1 Solving Electrical Insulation
Using standard fuses/VTs from air-insulated RMUs in gas-insulated compartments violates clearance standards. The solution is adopting insulation-compliant components, such as the JSZV16-10R VT. Features include:
- Integrated American-style cable accessories for full insulation.
- Built-in replaceable fuses at HV terminals.
- Rated voltage: 10/0.1/0.22kV.
Wiring configuration:
- Load switch side: European-style touchable T-type accessories.
- VT side: American-style 20kV touchable elbow accessories (compatible with VT fuses).
- Figure 4 shows the VT and American-style accessories.
All components are fully insulated and touchable. The limitation is the JSZV16-10R VT’s size (designed for compact outdoor RMUs), restricting 220V output to ≤2×400VA—sufficient for DC battery charging and lighting.
3.2 Solving Space Constraints
Validated layouts confirm insufficient space for VTs with cable accessories. Two solutions were tested:
- Top-mounted VT box: External cables and unsafe VT maintenance (violating interlocks).
- Bottom-mounted VT base (implemented):
- Extends the cable compartment downward.
- Height: 400mm, compatible with 700mm-high cable compartments.
- Enables mechanical interlocking for maintenance.
Result: This design ensures safe installation and maintenance while preserving gas-insulated RMU compactness.
