Medium voltage switchgear (MV) type Rotoblok SF

Characteristics

The Rotoblok SF type switchgear is a two compartment, indoors air insulated switchgear (AIS) in a mental enclosure made of zinccoated metal sheet (which ensures equipotential bonding), with a single primary busbars system. The switchgear is equipped with state-of-the-art, three-position disconnectors and switch disconnectors in SF₆ insulation.

The tank of each of these devices is constructed with stainless steel, which ensures maintaining a perfect technological condition of the switchgear over its entire operation period. It has separate primary busbars and cable compartments, and the arc-proof design ensures high level of operational safety.

The distribution bays have the following properties:

reduced dimensions compared to air insulated switchgear while maintaining high electrical parameters such as insulation level, rated currents and short-circuit current resistance,
two-compartment bay ensuring the separation of the primary busbar circuit from the section used to connect power supply cables,
high reliability of operation,
long operating period without the need for troublesome maintenance operations,
high corrosion resistance, the switchgear design uses zinc-coated metal sheet,
universality in designing different switchgear configurations with any number of bays,
use of state of the art, reliable switching devices, such as GTR SF type disconnectors and switch disconnectors (ZPUE), and VCB GIS type circuit breakers (ZPUE) or by other leading manufacturers,
adapted for the installation of state of the art protection and control devices,
the possibility of wall-mounting of the switchgear, saving space in the switching room, which is particularly important during retrofits and expansions of existing switching stations,
easy and quick access to switchgear devices for supervision and maintenance,
simple operation.

System of interlocks and protections

arc-proof design - resistance to internal arcing effects,
specially reinforced bay design (enclosures, locks, hinges),
mechanical interlocks, which prevent incorrect switching operations and touching live devices,
access to controlgear and control circuits is possible while the primary circuits parts cannot be touched by the operator,
the use of monitoring and signalling systems, and mechanical and electrical position indicators, and inspection windows,
use of three-position “on - off - earth” disconnectors and switch disconnectors with mechanical position indicators,
the use of fast earthing switch with an impulse drive,
the use of fast earthing switch with an impulse drive guarantee safety in case of an incorrect switch to a short-circuit.

Basic technical data

Compliance with standards:

The Rotoblok type switchgear meets the requirements of the following standards:

(PN-EN) IEC 62271-1 - “High-voltage switchgear and controlgear. Common specifications”,
(PN-EN) IEC 62271-200 - “High-voltage switchgear and controlgear. AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV standard,”
(PN-EN) IEC 62271-100 - “High-voltage switchgear and controlgear. Alternating-current circuit-breakers”,
(PN-EN) IEC 62271-102 - “High-voltage switchgear and controlgear. Alternating current disconnectors and earthing switches”,
(PN-EN) IEC 62271-103 - “High-voltage switchgear and controlgear. Switches for rated voltages above 1 kV up to and including 52 kV”,
(PN-EN) IEC 62271-105 - “High-voltage switchgear and controlgear. Alternating current switch-fuse combinations”.

Certified by the Electrotechnical Institute.

Basic electrical data:
	Rotoblok SF
Rated network voltage	20 kV
Highest device voltage	25 kV
Rated frequency / number of phases	50 Hz / 3
Rated short-time network frequency withstand voltage	50 kV / 60 kV
Rated withstand lightning surge voltage 1.2/50 μs	125 kV / 145 kV
Continuous rated current	630 A
Rated short-time withstand current	20 kA (1s)
Rated peak withstand current	50 kA
Resistance to internal arc effects	16 kA (1s)
IP protection rating	IP4X

Service conditions:
Ambient temperature
- peak short-time	+ 40°C
- highest day average	+ 35°C
- highest annual average	+ 20°C
- lowest long-term	+ 25°C¹⁾
Relative humidity of air
- highest day average	95%
- highest month average	90%
- highest day average vapour pressure	2,2 kPa
- highest month average vapour pressure	1,8 kPa
Atmosphere at the place of installation	no significant contamination with salt, vapour, dust, smoke, flammable or corrosive gasses and lack of icing, frosting and dewing
Installation altitude	up to 1000 m asl²⁾
Vibrations	vibrations caused by external factors or earthquakes negligible

Note:
^*1) Unless the manufacturer of instrumentation & control and protection devices has specified otherwise.
^*2) If the switchgear installation altitude is higher than 1000 m ASL the switchgear insulation level should corrected by an indicator in accordance with the guidelines of item 2.2.1 of the PN-EN 62271-1 standard.

Rated power of transformers that can be connected and disconnected using GTR SF 2V, GTR SF 2VM switch disconnectors, depending on voltages on the MV side:
Rated network voltage	Rated current	Max. transformer power
6 kV	77 A	800 kVA
10 kV	57,7 A	1000 kVA
15 kV	61,6 A	1600 kVA
20 kV	57,7 A	2000 kVA

In Rotoblok SF type switchgear typical fuse links are used acc. to the IEC 282-1, DIN 43625 standard, with thermal protection.

Switching devices

GTR SF 1 - switch disconnector with earthing switch,
GTR SF 1M - switch disconnector with earthing switch and motor drive,
GTR SF 2V - fused switch disconnector with earthing switch,
GTR SF 2VM - fused switch disconnector with earthing switch and motor drive,
GTR SF 4 - disconnector with earthing switch,
VCB GIS circuit breaker with disconnector and earthing switch.

Method of cable duct construction under Rotoblok SF and rotoblok SF type MV switchgears

The Rotoblok SF type switchgear is a two compartment, indoors air insulated switchgear (AIS) in a mental enclosure made of zinccoated metal sheet (which ensures equipotential bonding), with a single primary busbars system. The switchgear is equipped with state-of-the-art, three-position disconnectors and switch disconnectors in SF₆ insulation. The tank of each of these devices is constructed with stainless steel, which ensures maintaining a perfect technological condition of the switchgear over its entire operation period. It has separate primary busbars and cable compartments, and the arc-proof design ensures high level of operational safety.

Fig. 1 Cable duct proposal, to be constructed under Rotoblok SF switchgear

Example bays.
Cable duct under the switchgear.

Fig. 3 - Proposed depth of the cable duct under the Rotoblok SF switchgear

Dry single-core cable

Cable cross-section (mm²)	Bending radius (mm)	Tray depth k (mm)
50	370	400
70	400	430
95	440	470
120	470	500
150	500	550
185	540	600
240	590	700

Rotoblok SF switchgear cable connections

Feeder bay

Cable type	Cable termination
	Manufacturer	Type		Cable cross-section [mm²]
Single-core with plastic insulation e.g. YHAKXs, YHKX, XUHAKXs, XRUHKs, ...	CELLPACK	CHE-I 24kV		25-150
				70-240
		CAE-I 24kV		35-120
				70-240
		CAESK-I 24kV		70-150
				120-240
	Nexans (EUROMOLD)	ITK224 (stretch sleeve)		25-240
		AIP20 (slip-on)		25-120
		AIS20 (slip-on)		70-300
		AIN20 (slip-on)		25-1200
		24MONOi1 (shrink sleeve)		25-240
	TYCO ELECTRONIC	Rated voltage	Type (stretch sleeve)
		6/10	POLT-12xxx	25-1200
		8,7/15 i 12/20	POLT-24xxx	25-800
		18/30	POLT-42xxx	35-800

Note!
The manufacturer should be consulted regarding the manner of connection of cables and used terminations.

Transformer bays

Single-core with plastic insulation e.g. YHAKXs, YHKX, XUHAKXs, XRUHKs, ...	As in feeder bays
Tri-core oil-filled with paper insulation saturated with non-running saturant and common coating, e.g.: HAKnFta, KnY, KnFTA, ...	The manufacturer should be consulted regarding the manner of connection of cables and used terminations

Note!
In all cases a cable duct is required under the switchgears. As an option the switchgear may be placed on a raised base or on a raised floor.
In case other type of terminations is used, please contact the manufacturer

Construction of switchgear type Rotoblok SF

Side view and dimensions

Rotoblok SF - Side view and dimensions

- Stainless steel tank filled with SF₆ gas with switching devices
- Drive mechanism compartment
- Insulating bushings
- Safety valve

Note!
Figures shown on subsequent pages are only an example of bay equipment. It is possible to adapt the bay configuration to specific requirements of the end user. In this case manufacturer should be asked to provide drawings.

SL1 (line feeder)

Electrical diagram