WALK-ON TRANSFORMER STATIONS

Substations With Indoor Service

GRITEC walk-on substations can meet even the most demanding requirements. We fit them with 4.8 MVA transformers, and even more powerful ones for special projects. The stations are a walk-in design, accessible from inside for operating personnel. Due to their dimensions,the stations form a distinctive feature in a built-up or rural area. For that reason, we offer a range of surface finishes and technologies for conveniently blending the buildings into their settings.

SUMMARY DESCRIPTION AND COMPARISON WITH THE COMPACT SUBSTATIONS

STATION TYPE AND CODE	WALK-ON	COMPACT
GRITEC model series code	UF	UK
Operator access	walk-in	non walk-in
Height from ground	approx. 2.8 m	approx. 1.5 m less than 1m for underground (or, half-buried) stations
Footprint	approx. 6–25 m2	approx. 3–6 m2
Weight, equipment exclusive	13–50 t	7–13 t
Transport	oversize load	common road truck
Transformer output power	up to 4.8 MVA, or more depending on project	normally 630 kVA, up to 2.5 MVA depending on project
Transformer placed on	rails	on transformer station floor
Transformer replacement	through door	following roof dismantling

ELECTRICAL TECHNOLOGIES

As a rule, 4.8 MVA transformers are used to fit out the walk-on stations. The transformer output power may be increased for special projects. Oil and dry transformers are normally placed on steel sections (transformer rails) and their potential replacement is executed through the transformer vault door. An oil retention pit is ready under the transformer.

Robust, patented cable grommets serve as passthroughs for all standardised cables used in the power engineering industry. Grommets from other manufacturers may be supplied upon request.

The HV and LV switchgears are placed on the raised floor of the substation that is as a rule separated by a concrete partition wall from the transformer vault, and accessible through a separate door. The HV switchgears up to 35 kV voltage may be both compact and modular, and SF6 gas or air insulated. The LV switchgears are a cabinet or wall-mounted design and may be deployed at high rated currents up to 3,500 A.

The measuring boxes (USMs, universal measuring boxes) are installed in the external wall cutouts, thus providing for their accessibility also from the outside.

BUILDING AND STRUCTURAL SOLUTION

The body of a station is comprised of 4 external walls, at a minimum thickness of 10cm, and a bottom at a minimum thickness of 12cm. We precast the body using the “bell casting” method, as a single seamless casting. The manufacturing method gives the following features to the body:

exceptional mechanical resistance. The body is a self-supporting box type element and, as a result, it needs no foundation and may also serve as a retaining wall when set in a slope
perfect tightness; the cast-in-place, seamlessconcrete body is watertight, serving at the sametime as an impermeable pit to catch oil in case ofa transformer accident,
easy transportability, based again on the mechanical stability of the body itself,
long service life and reliability.

We make the body, roof and partition walls from impermeable concrete of C35/45 strength class and XC4 and XF1 exposure classes compliant to EN 206-1.

The roofs may serve also for ventilation and for overpressure exhaust in case of internal short circuit. As is standard, we fit the transformer stations with a flat reservoir roof that may be additionally vented along its perimeter. Upon request, we will execute any sloped roof solution with clad or sheet metal roofing.

The false floor is executed either from concrete or using an extruded aluminium shape system. The concrete raised floor benefits from being fire safe, while the aluminium shape system offers a high degree of flexibility. We mount the aluminium shapes on adjustable galvanised steel supports. The tread layer is of plywood with self-extinguishing and slip resistant surface treatment. The floor panels are fitted with a key operated latch preventing their accidental lifting.

The partition walls are at least 8 cm thick, while their actual thickness and position are optional.

IRONMONGERY PRODUCTS

We make the doors and ventilation elements from anodized aluminium in our in-house METALLBAU machine shop.

More about METALLBAU

TYPES AND DIMENSIONS

Type series UF 25

Typ	L inner [m]	B inner [m]	H inner [m]	L outer [m]	B outer [m]	H* outer [m]	Zastav. plocha [m²]	Enclosed area [m³]	Weight [t]
2524	2,18	2,30	3,20	2,38	2,50	3,32	5,95	20,35	14,51
2530	2,78			2,98			7,45	25,48	16,65
2536	3,38			3,58			8,95	30,61	18,78
2542	3,98			4,18			10,45	35,74	20,91
2548	4,58			4,78			11,95	40,87	23,05
2554	5,18			5,38			13,45	44,65	25,18
2560	5,78			5,98			14,95	49,63	27,31
2566	6,38			6,58			16,45	55,49	31,74
2572	6,98			7,18	2,54		18,24	60,55	35,08
2578	7,58			7,78			19,76	65,61	37,50
2584	8,18			8,38			21,29	70,67	39,92

* Outside height without roof plate.

Type series UF 30

Typ	L inner [m]	B inner [m]	H inner [m]	L outer [m]	B outer [m]	H* outer [m]	Built-up area [m²]	Enclosed area [m³]	Weight [t]
3024	2,18	2,78	3,20	2,38	2,98	3,32	7,09	24,25	16,57
3030	2,78			2,98			8,88	30,37	18,90
3036	3,38			3,58			10,67	36,49	21,23
3042	3,98			4,18			12,46	42,61	23,56
3048	4,58			4,78			14,24	48,70	25,89
3054	5,18			5,38			16,03	54,82	30,11
3060	5,78			5,98			17,82	60,94	32,65
3066	6,38			6,58			19,61	67,07	35,19
3072	6,98			7,18	3,02		21,68	74,58	38,90
3078	7,58			7,78			23,50	80,84	41,53
3084	8,18			8,38			25,31	87,07	44,17

* Outside height without roof plate.

Type series UF 33

Typ	L inner [m]	B inner [m]	H inner [m]	L outer [m]	B outer [m]	H outer [m]	Built-up area [m²]	Enclosed area [m³]	Weight [t]
3342	3,98	3,08	3,20	4,18	3,28	3,32	16,00	55,04	25,60
3348	4,58			4,78	3,32		16,00	55,04	29,81
3354	5,18			5,38			17,99	61,89	32,55
3360	5,78			5,98			19,99	68,77	35,28
3366	6,38			6,58			21,98	75,61	38,02
3372	6,98			7,18			23,97	82,46	40,76
3378	7,58			7,78			25,96	89,30	43,50
3384	8,18			8,38			27,95	96,15	46,24

Type series UF 36

Typ	L inner [m]	B inner [m]	H inner [m]	L outer [m]	B outer [m]	H outer [m]	Built-up area [m²]	Enclosed area [m³]	Weight [t]
3642	3,98	3,38	3,20	4,18	3,58	3,32	14,96	49,68	27,30
3648	4,58			4,78	3,62		17,30	57,45	31,65
3654	5,18			5,38			19,48	64,66	34,52
3660	5,78			5,98			21,65	71,87	37,39
3666	6,38			6,58			23,82	79,08	40,26
3672	6,98			7,18			25,99	86,29	43,13
3678	7,58			7,78			28,16	93,50	46,00
3684	8,18			8,38			30,34	100,71	48,87

IMPLEMENTATION

For the sake of accelerating construction works, we install the electrical technologies in the station already at the production plant. Self-standing stations are placed on a prepared ballast course without foundations. Foundations are required only for combination multi-body buildings. We haul walk-on stations as an oversize load and use a crane to place them. The weight, equipment exclusive, ranges from 13 to 50t. The engineering structure user provides for the base course preparation and for external cabling and earthing execution.

SAFETY

Our priority is to protect health and assets. Our products conform to all requirements placed on them by the standards and regulations. Thanks to our innovative solutions, we stand ready to provide even stronger protection and safety levels upon request.

More about safety