What is a portable ground and why you need it ?

device

is made of a flexible, copper cable without a braid, with devicestype fastening clamps with insulated handles bridging phases and connection to the ground bus.There are three-phase devices for structurally union of four earth electrodes in a single device or separately to the bus and ground phase.

Looks portable ground as pictured:

clamp design allows their installation with a special insulating rod.Combining lived in a three-phase earthing produced crimping or welding, bolting is allowed, but the core should be luzheny brazing crimp in place.Simply mount soldering is not allowed, since the short-circuit currents can heat up the connection and destroy the integrity of the device.

visually see what a portable ground and how to use it properly, you can in the video tutorial below:

The requirements

cable and mount the portable device must withstand currentshort circuit and dynamic loads.Clamps ensure good contact, to be heat-resistant.Cross section for installations up to 1000 V is not less than 16 mm.Above 1000 volts conductors not less than 25 mm.

At voltages higher than 6 kV conductor cross section is 120 mm or more, which is not practical and difficult.Therefore allowed to install multiple grounding side, a total of picking up the right section.

Use wire insulation for wire grounding is prohibited because the insulating layer is difficult to detect in time the damage was living conductor and reducing the calculated cross section, which can lead to burnout earthing.

section

Calculation Calculate the required conductor cross-section can be on a simplified formula:

S = (Iset √tf) / 272

where:

• Iset - the steady short-circuit current.A;
• tfr - fictitious time, sec;

When grounding calculations for distribution devices of voltage tfr take the most important time of drawdown relays electrical protection.In networks with a grounded neutral conductor cross-section is calculated by the current short-circuit of one phase.

procedure for installing and removing

Installation is performed on de-energized busbar section on the side on which the possible supply voltage.Before installation check for a pointer to the current carrying tire stress, making sure his absence, installing portable earthing.First attach the clamps to the zero bus or a grounded structure, and then turn on the phase.Install clips made using insulated rod, using safety equipment, wearing boots and gloves, as shown in the picture:

If the land on which work is divided switchgear, or produced with dismantling tires, ground is applied to both sides of theplaces of work, to prevent tip-off voltage of the next busbar runs.

Installing temporary ground made from the floor or the ground, the rise in the ground is not yet prohibited equipment without re-verification voltage.Removing temporary ground in reverse order.First, they removed the clamps from the busbar, then removed from the grounded conductor element or zero tire.To remove a portable ground must be isolated by a rod and protective equipment.After removing the jumpers must not touch the tires without protection, as they may be induced voltage.

The video examples below demonstrate how to install a portable ground:

Remember, manufacturingIt works in electrical installations made on the permit, accompanied by an observer, with the instructions before starting the work, according to valid regulations on TB and the rules of technical operation.

That's all that I wanted to tell you that is a portable ground, how to install it and what are the requirements for conductor cross-section.We hope the information was useful and understandable for you.

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