Electrical Distribution Equipment for Energy Systems

	Medium voltage electric cells

	Primary distribution cells also called "substation cells"

	Secondary distribution cells also called "transforming substation cells"

	AlfaPower - Prefabricated Substation

Metallic enclosures

Equipment for it and telecom industry

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Applications

Secondary distribution cells also called "transforming substation cells"

Designation

The medium voltage CIS type electric cells for secondary distribution are used for the medium voltage section of the MV/LV substations in the power system, as well as in the supply units of the power distribution systems, in public networks, for individual consumers, as well as in industrial electric networks. According to the cell type, they may be supply, distribution and measuring cells.

The type and equipment of each cell determine their main functions: commutation, protection, local or remote control, data transmission or collection etc. The medium voltage CIS type cells are mounted in closed rooms on an horizontal metal frame erected directly on the floor.

Technical characteristics:

Characteristic	U.M.		Value
Rated average voltage	kV		24
Rated average lightning-resistance voltage (phase-ground, phase-phase)	kV		125
Rated 50Hz test resistance voltage	kV		50
Rated current (In): • bus-bars • circuit breaker • current trafo	A		max. 630 max. 630 max. 630
Breaking current	kA		max.16
Peak admissible rated current	kAmax		max.40
Short duration admissible rated current	kAef		max.16/1s
Rated frequency	Hz		50
Secondary and control circuits voltage	V	d.c.	24; 48; 60; 110;220(**)
		a.c.	100; 110; 230(**)
Usual protection functions	ANSI code (***)		27; 50; 50N; 51; 51N; 59
Normal protection degree: • in the work position, with all the doors and panels closed • between neighboring inner compartments			IP 3X IP 2X
Bar insulation in the main circuits			air
Free electric arc resistance inside de cells	KA		16 KA

* upon request, protections may be self-supplied
** according to the beneficiary’s order; other values are also available upon request;
*** the protections according to the ANSI codes are as follows:

27. protection at minimum voltage;
50. overcurrent (short-circuit) instantaneous protection;
50N. homopolar overcurrent instantaneous protection;
51. overcurrent (overload) delayed protection;
51N. homopolar overcurrent delayed protection;
59. maximum voltage protection;

According to the beneficiary’s order; other protection functions are also available upon request.

Operational sections

Medium voltage circuits compartment

This compartment houses the medium voltage equipment, according to the destination of the SF6 load separator cell, possibly associated with a mean voltage fuse support, or with a circuit breaker, it also includes the current measurement transformers, the voltage measurement transformers, the variable resistance arresters and capacitive insulators indicating the presence of voltage on the points of the secondary circuit where they are located.

Secondary circuits compartment

This compartment houses the secondary circuits and the minimum voltage protection relays, which may be mounted inside the compartment or on the compartment door, together with the measuring equipment and the signaling lamps. The low voltage secondary circuits are located in a separate compartment from the main medium voltage circuits.

Structural information

A. The case is provided with a slotted cover and double wall (behind the cell) for the gas exhaustion as a consequence of a free electric arc, their direction being to the upper part.
B. The removable panels or access panels to the under voltage parts of the cell are provided with warning marks “WARNING! DANGER OF DEATH!” The dismantling of these panels is carried out according to the technical manual provisions.
C. In the cell compartments it is provided a resistance connected by a thermostat in order to eliminate the condensing water. The inside of the cell should be lighted by lamps fitted in the secondary circuit compartment
D. The support insulators are made of cast epoxy resin.
E. The cells are provided with a general earthing bar that provides the circuit continuity with the possibility of connection to the earthing socket of the electric station
F. All the cells are provided with the facility of connecting the medium voltage cables (max. 2 cables per phase) on the corresponding connection terminals
G. The cells are extensible, being designed so that to easy introduce new cells in an electric station
H. The cell are provided with extensible general bar bridge and with distribution bars, preferably made of copper.
I. The cells are provided with terminals fixed with screws for medium voltage cables mounting.
J. The input of the cables from the cable channel to the cells is carried out through cuttings executed through the cell basic plan. These cuttings are obturated with pre-cut aluminum covers and insulating plates which are cut according to the connection cable dimensions.
K. The secondary circuits are separated from the medium voltage area by metallic screens or, on short distances by insulated tubes. All the cells are provided with the facility of passing the secondary circuit cables to the secondary circuit compartment. The connections between the secondary circuits of a electric station cells are carried out by the cable tunnel placed above the secondary circuit compartment.

Product variants:

Other information:

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