Hardware terminal clamps

Hardware terminal clamps , type A1M, A2M and A4M for copper conductors, type A1A, A2A, A4A type for aluminum and steel-aluminum conductors and clamps, type A2AП, A4AП and A6AP for attachment of aluminum conductors are used for switchgear assembly. Hardware terminal clamps have better performance indicators since they do not require periodic tightening of bolts.

Clamp marking shall be read in the following way: for example, make A2A-120, where:

A – hardware clamp ;

2 – number of holes in a contact pad;

A – used for aluminum (steel-aluminum) conductors.

In some cases for busbar insulation of outdoor switchgear at the substations there is a need of connection of two, three and more wires of a bundle phase to the equipment.

Hardware terminal clamp for connection of two, three, four and five wires to the equipment terminals consists of the tube suitable for a press fitting and having contact pads. Connection of contact pads with equipment terminal is made with the aid of 2, 4, 6 and more bolts. The major makes of the clamps are following:

2A2A, 2A4A, 2A6A – for connection of two aluminum (steel-aluminum) conductors to the equipment terminals;

2A4AП, 2A6AП – for connection of two hollow aluminum conductors to the equipment terminals;

3A2A, 3A4A – for connection of three aluminum (steel-aluminum) conductors to the equipment terminals;

3AAП, 3A2AП, 4A6AП, 5A2AП – for connection of three, four or five conductors to the equipment terminals.

Clamp marking shall be read in the following way: for example, make 2A4A-500-4, where:

2 – number of the conductors connected to the equipment;

A – terminal clamp;

4 – number of holes in a contact pad (number of bolts for fastening the contact pad to the equipment terminal);

A – for aluminum (steel-aluminum) conductors;

500 – cross-section in mm² of the intended conductor;

4 – serial number of a clamp make.

The AП index in the clamp marking means that the clamp is intended for an aluminum hollow conductor.

Hardware terminal clamps for two and three wires/conductors are made of the special shapes or commercial grade aluminum pipes.

Two clamp versions are available:

version 1 – the conductors linked up with the equipment are located perpendicular to the contact pads;

version 2 – conductors’ axis are parallel to the contact pads.

Contact surfaces of the clamp pads may come copperplated (by plasma flame spraying) or blank, as per request of the customer. Compression clamps are pressure-mounted on conductors by means of hydraulic press, type МИ-2А, МИ-1Б, П-100М or УП-320. Clamps for wires of a cross-section up to 185 mm ² can be also pressed by hand crimp tool, type МИ-248 also. Clamps are intended, mainly, for fixing conductors to the equipment terminals and for use with T-connectors. Each clamp has relevant marking, manufacturer’s trademark, and year of manufacture. The clamp-connected conductors shall have electrical resistance not exceeding resistance of a conductor/wire of the same length. The clamp heating at a current density that is maximum for the specific conductor grade, shall not exceed heating of a conductor/wire itself. Crimping strength of the hollow conductors which are cut and clamped in the T-connectors provides at least 90% of the strength of the intact conductor.
Clamp assembly shall be carried out in the strict accordance with the requirements of installation manual and instructions on drawings.