Product Overview
ABB SafeRing Air and SafePlus Air are SF₆-free, gas-insulated medium-voltage switchgear systems designed for secondary distribution networks up to 12 kV and 630 A. They use Dry Air as the insulating medium, providing a low-carbon alternative to conventional SF₆-insulated switchgear.
All live components and switching functions are enclosed inside a fully sealed stainless-steel gas tank with an IP67 degree of protection. The sealed design maintains stable internal atmospheric conditions and protects the equipment against dust, moisture, condensation, and other external environmental influences.
SafeRing Air is a compact ring main unit intended for secondary distribution networks, while SafePlus Air is a flexible metal-enclosed compact switchgear system supporting semi-modular and fully modular configurations.
The product family is based on the established SafeRing/SafePlus platform and retains the same user interface, operating procedures, components, and spare parts. Configurations of up to five functional units can be installed in one common gas tank.
Typical applications include:
- Secondary distribution networks
- Compact secondary substations
- Utility distribution systems
- Commercial and residential buildings
- Light industrial facilities
- Wind and solar power plants
- Airports and hospitals
- Tunnels and underground railways
- Hotels, shopping centers, and office buildings
- Light mining applications
Product Features
SF₆-Free Insulation
SafeRing Air and SafePlus Air use Dry Air instead of SF₆ as the insulating medium.
Environmental advantages include:
- SF₆-free switchgear technology
- Dry Air with a global warming potential of zero
- No direct contribution to global warming from the insulating gas
- Reduced environmental footprint
- Climate-friendly medium-voltage distribution solution
- No special SF₆ handling requirements
Fully Sealed Construction
All live parts and switching components are enclosed inside a stainless-steel gas tank.
Construction benefits include:
- IP67 gas tank protection
- Protection against dust and moisture
- Protection against humidity and condensation
- Constant internal atmospheric conditions
- High operational reliability
- Enhanced personnel safety
- Virtually maintenance-free operation
- Gas leakage rate not exceeding 0.05% per year
Compact and Modular Design
Each standard functional module is only 325 mm wide, enabling compact installation in locations with restricted space.
Configuration features include:
- One-way to five-way configurations
- Up to five functional units in one common gas tank
- Semi-modular configurations
- Fully modular configurations
- Compact installation footprint
- Easy transport and installation
- Compatibility with the existing SafeRing/SafePlus portfolio
Flexible Functional Units
The SafeRing/SafePlus Air portfolio includes switching, protection, sectionalizing, metering, and direct cable connection modules.
Available modules include:
| Code | Functional unit |
|---|---|
| C | Cable switch module with vacuum load-break switch |
| V | Vacuum circuit-breaker module |
| D | Direct cable connection module |
| SlBr | Busbar sectionalizer with vacuum load-break switch |
| SvBr | Busbar sectionalizer with vacuum circuit breaker |
| PTC | Voltage transformer panel with disconnector |
| M/PT | Metering or voltage transformer module |
Safe and Simple Operation
The switchgear is designed to simplify installation, operation, and maintenance.
Safety and operating features include:
- Integral mechanical interlocks
- Interlocking between switching and earthing functions
- Clear mechanical position indicators
- Cable covers interlocked with the earthing switch
- Padlocking facilities for switching functions
- Optional key interlocks
- Capacitive voltage indication
- Optional fault passage indication
- Factory-assembled and routine-tested units
- No special installation tools required
Vacuum Switching Technology
Vacuum technology is used for load switching and circuit-breaker interruption.
Advantages include:
- Reliable load switching
- Short-circuit interruption through the V module
- High electrical endurance
- High mechanical endurance
- Reduced maintenance
- Compact switching components
- Motor operation available as an option
Protection and Automation
SafePlus Air can accommodate self-powered or auxiliary-powered protection relays.
Available protection and automation options include:
- Self-powered electronic protection relays
- ABB REJ603 protection relay
- ABB REX615 protection and control relay
- ABB REF615 protection relay
- Transformer protection
- Feeder and cable protection
- Short-circuit protection
- Earth-fault protection
- Remote control
- Remote monitoring
- Fault passage indication
- Current measurement
- Voltage measurement
A low-voltage compartment is required for selected protection, communication, remote control, and monitoring equipment.
Main Functions
Ring Main Distribution
SafeRing Air provides switching, sectionalizing, and cable connection functions in secondary ring distribution networks.
It supports:
- Ring network switching
- Incoming and outgoing cable control
- Feeder isolation
- Cable earthing
- Network sectionalizing
- Faulted section isolation
- Service restoration
Load Switching
The C module incorporates a 630 A vacuum load-break switch for normal load-current switching.
Its principal functions include:
- Making and breaking normal load current
- Isolating a cable feeder
- Earthing the downstream cable
- Mechanical position indication
- Manual or optional motor operation
- Interlocking between the load-break switch, disconnector, and earthing switch
Short-Circuit Protection
The V module incorporates a 630 A vacuum circuit breaker with a short-circuit breaking capacity of 20 kA.
Its functions include:
- Normal load switching
- Short-circuit current interruption
- Transformer protection
- Feeder protection
- Relay-controlled tripping
- Cable isolation and earthing
- Optional remote opening and closing
Disconnection and Earthing
Three-position disconnector and earthing switch assemblies provide safe isolation and earthing.
Functions include:
- Connected position
- Disconnected position
- Earthed position
- Mechanical interlocking
- Position indication
- Safe cable compartment access
- Prevention of unsafe operating sequences
Busbar Sectionalizing
The SlBr and SvBr modules divide the main busbar into separate sections.
SlBr module
- Busbar sectionalizing by vacuum load-break switch
- 630 A normal current
- Disconnector and earthing functions
- Optional motor operation and auxiliary contacts
SvBr module
- Busbar sectionalizing by vacuum circuit breaker
- 630 A normal current
- Short-circuit protection capability
- Optional protection relay and current transformers
- Optional remote operation
Direct Cable Connection
The D module provides a direct cable connection to the main busbar without an integrated switching device.
It includes:
- Front horizontal cable bushings
- Interface C cable connections
- Integrated voltage divider
- 630 A main busbar
- Earthing bar
- Optional measuring current transformer
- Optional surge arrester
- Optional double cable connection
Metering and Voltage Measurement
The M/PT, PT, and PTC modules support electrical measurement and voltage transformer applications.
Available functions include:
- Current measurement
- Voltage measurement
- Energy metering
- Two or three current transformers
- Two or three voltage transformers
- Voltage transformer fuse protection
- Optional surge protection
- Optional DC charger and battery
The PTC module additionally provides a three-position disconnector and earthing switch.
Voltage Presence Indication
The switchgear supports both VPIS and VDS voltage indication systems.
VPIS
- Indicates the presence of medium voltage
- Provides front-panel phase connection points
- Supports phase comparison
- Supports indicator testing
The absence of a VPIS indication must be confirmed with suitable voltage detection equipment.
VDS
- Detects the presence or absence of medium voltage
- Supports safe verification before operation or maintenance
Fault Passage Indication
Optional fault passage indicators assist operators in identifying and locating faults in distribution networks.
Detectable conditions include:
- Short-circuit faults
- Earth faults
- Fault current direction
Fault information can be indicated locally and, depending on the selected device, transmitted remotely.
Protection Relay Functions
SafePlus Air supports auxiliary-powered and self-powered protection relays.
Auxiliary-powered relays
These relays can provide:
- Feeder and line protection
- Transformer protection
- Machine protection
- Capacitor protection
- Voltage protection
- Busbar protection
- Arc protection
- Interconnection protection
- Control and communication functions
Self-powered relays
Self-powered relays are suitable for locations where an auxiliary supply is unavailable or cannot be guaranteed.
The REJ603 provides:
- Selective short-circuit protection
- Earth-fault protection
- Feeder protection
- Small transformer protection
- Current-transformer-powered operation
Key Interlocking
Optional bolt-type key interlocks can coordinate operating sequences between different switchgear units or connected equipment.
They can be used to:
- Prevent earthing of an energized incoming cable
- Prevent closing a load-break switch while another feeder is earthed
- Control access to transformer compartments
- Ensure the transformer primary side is earthed before access
- Coordinate safe operation between interconnected switchgear assemblies
Specifications
General Electrical Ratings
| Parameter | SafeRing/SafePlus Air |
|---|---|
| Rated voltage | 12 kV |
| Rated continuous current | 630 A |
| Rated short-time withstand current | 20 kA for 4 s |
| Power-frequency withstand voltage | 28/32 kV |
| GB power-frequency withstand parameter | 42/48 kV |
| Lightning impulse withstand voltage | 75/85 kV |
| Insulating medium | Dry Air |
| Rated gas pressure | 1.4 bar at 20°C |
| Gas leakage rate | ≤ 0.05% per year |
| Internal arc classification | IAC AFLR, 20 kA for 1 s |
| Gas tank protection | IP67 |
| External enclosure protection | IP4X |
| Main busbar current | 630 A |
C and V Module Performance
| Parameter | C Module | V Module |
|---|---|---|
| Switching device | Vacuum load-break switch | Vacuum circuit breaker |
| Rated voltage | 12 kV | 12 kV |
| Rated continuous current | 630 A | 630 A |
| Short-time withstand current | 20 kA for 4 s | 20 kA for 4 s |
| Active-load breaking capacity | 630 A | — |
| Short-circuit breaking current | — | 20 kA |
| Making capacity of main switching device | 50 kA | 50 kA |
| Earthing-switch making capacity | 50 kA | 50 kA |
| Electrical class of main switching device | E3 | E2 |
| Earthing-switch electrical class | E2 | E2 |
| Mechanical endurance of main switching device | 5,000 operations | 5,000 operations |
| Mechanical endurance of disconnector | 3,000 operations | 3,000 operations |
| Mechanical endurance of earthing switch | 3,000 operations | 3,000 operations |
| Operating sequence | — | O – more than 3 min – CO – more than 3 min – CO |
Environmental Conditions
| Parameter | Specification |
|---|---|
| Maximum ambient temperature | +40°C |
| Maximum 24-hour mean temperature | +35°C |
| Minimum ambient temperature | −25°C |
| Special minimum temperature | −40°C, subject to ABB consultation |
| Maximum 24-hour mean relative humidity | ≤ 95% |
| Maximum monthly mean relative humidity | ≤ 90% |
| Standard installation altitude | ≤ 1,500 m |
| Special installation altitude | Up to 3,000 m, subject to ABB consultation |
Internal Arc Classification
| Item | Specification |
|---|---|
| Classification | IAC AFLR |
| Arc-fault current | 20 kA |
| Arc-fault duration | 1 s |
| Accessibility | Front, lateral, and rear |
Gas System
| Item | Specification |
|---|---|
| Insulating gas | Dry Air |
| Global warming potential | 0 |
| Rated pressure | 1.4 bar at 20°C |
| Maximum leakage rate | 0.05% per year |
| Tank material | Stainless steel |
| Tank construction | Fully sealed for life |
| Tank degree of protection | IP67 |
Standard SafeRing Air Equipment
SafeRing Air is supplied with:
- Downstream earthing switches
- Operating mechanisms with integral mechanical interlocking
- Operating handle
- Padlocking facilities
- Front cable bushings
- Cable compartment covers
- Lifting lugs
- 630 A main busbar
- Earthing bar
- Capacitive voltage presence indication system
Optional Equipment
Available options include:
- Cable cover with inspection window
- Cable cover for double T-connectors
- Opening trip coil
- Opening and closing trip coils
- Motor operation
- Auxiliary contacts
- Relay test facilities
- Short-circuit indicator
- Circuit-breaker tripped signal
- Current metering
- Low-voltage compartment
- Top cable entry box
- Ronis key interlock
- Self-powered protection relays
- ABB REJ603 relay
- ABB REF615 relay
- ABB REX615 relay
- Surge arresters
- Double cable connections
- Protection and measuring current transformers
C Module
Standard equipment
- 630 A vacuum load-break switch
- Two-position single-spring operating mechanism
- Downstream three-position disconnector and earthing switch
- Three-position single-spring mechanism
- Mechanical interlocking
- Switch position indication
- Front horizontal Interface C cable bushings
- Integrated voltage divider
- Earthing-switch-interlocked cable cover
- 630 A main busbar
- Earthing bar
Optional equipment
- Motor operation
- Load-break switch auxiliary contacts: 2 NO + 2 NC
- Disconnector auxiliary contacts: 2 NO + 2 NC
- Earthing switch auxiliary contacts: 2 NO + 2 NC
- Short-circuit indicator
- Double cable connection
- Surge arrester
- Top extension
- Low-voltage box
- Measuring current transformer with meter
V Module
Standard equipment
- 630 A vacuum circuit breaker
- Two-position double-spring operating mechanism
- Downstream three-position disconnector and earthing switch
- Three-position single-spring mechanism
- Mechanical interlocking
- Position indication
- Self-powered electronic protection relay
- Ring-core current transformers installed on cables
- Relay-operated trip coil
- Front horizontal Interface C cable bushings
- Integrated voltage divider
- Earthing-switch-interlocked cable cover
- 630 A main busbar
- Earthing bar
Optional equipment
- Motor operation
- Opening trip coil
- Opening and closing coils
- Circuit-breaker auxiliary contacts: 2 NO + 2 NC
- Disconnector auxiliary contacts: 2 NO + 2 NC
- Earthing switch auxiliary contacts: 2 NO + 2 NC
- Circuit-breaker tripped signal: 1 NO
- Short-circuit indicator
- Double cable connection
- Surge arrester
- Top extension
- Low-voltage box
- ABB REF615 protection relay
- Protection current transformer
- Measuring current transformer with meter
Cable Bushings
| Item | Specification |
|---|---|
| Standard interface | Interface C |
| Series | 400 series |
| Rated current | 630 A |
| Contact | M16 bolted contact |
| Construction | Epoxy resin with molded-in conductors |
| Electrical field control | Integrated molded screen |
| Voltage indication | Integrated capacitive voltage divider |
| Applicable standards | CENELEC EN 50181 and IEC 60137 |
| Optional sensor version | Integrated voltage and current sensors |
When a cable is not connected, the earthing switch must be locked in the closed position or the bushing must be fitted with an appropriate dead-end receptacle before energization.
Overall Configuration Widths
Each functional module adds approximately 325 mm to the assembly width.
| Configuration | Dimension B | Dimension C |
|---|---|---|
| 1-way | 371 mm | 297 mm |
| 2-way | 696 mm | 622 mm |
| 3-way | 1,021 mm | 947 mm |
| 4-way | 1,346 mm | 1,272 mm |
| 5-way | 1,671 mm | 1,597 mm |
Protection Relays
| Relay | Power supply | Main application |
|---|---|---|
| REX615 | Auxiliary powered | Configurable protection and control for power generation and distribution |
| REF615 | Auxiliary powered | Feeder and transformer protection |
| REJ603 v1.5 | Self-powered | Transformer, cable, short-circuit, and earth-fault protection |
| REJ603 v3.0 | Self-powered | Protection with LCD, LED indication, measurements, events, and settings |
REJ603 ring-core CT ranges
| CT type | Current range |
|---|---|
| CT1 | 8–28 A |
| CT2 | 16–56 A |
| CT3 | 32–112 A |
| CT4 | 64–224 A |
| CT5 | 128–448 A |
Applicable Standards
| Standard | Description |
|---|---|
| IEC 62271-1 | Common specifications for high-voltage switchgear and controlgear |
| IEC 62271-100 | High-voltage AC circuit breakers |
| IEC 62271-102 | AC disconnectors and earthing switches |
| IEC 62271-103 | Switches for rated voltages above 1 kV up to and including 52 kV |
| IEC 62271-200 | AC metal-enclosed switchgear and controlgear above 1 kV up to and including 52 kV |
| IEC 60137 | Insulated bushings for alternating voltages above 1 kV |
| CENELEC EN 50181 | Plug-in type bushings for equipment above 1 kV up to 52 kV |
