Electrical Safety Common Questions

What is safety voltage?

Safety voltage is in order to prevent electric shock accidents, and the use of a specific power supply voltage series, according to the environment, personnel and use mode, China's safety voltage is 42 volts, 36 volts, 24 volts, 12 volts, and 6 volts 5, commonly used safety voltage is 36 volts, 12 volts.

A copper conductor with a cross-sectional area of 2.5 mm ² allows a long-term current of 16-25A.

How are high pressure and low pressure divided?

High voltage: where the ground voltage in 250 volts and above is high voltage, in the AC system, 1 kv, 3 kv, 6 kv, 10 kv, 35 kv are high voltage, in the DC system 500 volts is high voltage.

Low voltage: any ground voltage of 250 v and below is low voltage. 220V, 110V ac system and 380/220 v and 220/110 v neutral ground system of three-phase four-wire system are low voltage.

Attention should be paid to the maintenance of high-voltage motors: first implement safety measures for power outage, and then carry out maintenance work in the circuit of high-voltage motors and their auxiliary devices; At the end of the maintenance work, when it is necessary to electrify the experimental high-voltage motor and its starting device, all the staff should be evacuated from the site before sending power for test operation.

What is voltage to earth?

When an electrical device is short-circuited to earth, its grounding part, such as the grounding body, grounding wire, equipment shell, etc., is called the voltage to earth when the potential difference is equal to zero with the earth potential.

What is insulation? How many types of insulation are there?

The use of non-conductive material will be charged body isolation or screen up, to prevent the human body electric shock measures, called insulation. Insulation is usually divided into; Gas insulation, liquid insulation and solid insulation.

How does static electricity come about? What harm does it do?

Most static electricity in work, production and life is caused by the contact and separation of different substances or friction with each other.

The harm of static electricity is basically the human body by electric shock, affect product quality and cause combustion and explosion three aspects, which cause combustion and explosion is the most serious, can lead to casualties and property losses. For places prone to static electricity, to keep the air moist; Staff should wear antistatic clothes and shoes.

What does electrician safety have?

Electrical safety appliances include; Insulation safety appliance (basic safety appliance, auxiliary safety insulation appliance), safety appliance for ascending operation, portable voltage and current indicator, ground wire for maintenance, barrier sign, and equipotential shielding shunt voltage uniform for live use, etc.

Why basic safety insulation? What are the basic safety insulation requirements for high and low voltage power?

The safety appliance that its insulation strength enough bears electric equipment to run voltage calls basic safety insulation appliance.

High voltage basic safety insulation; High voltage insulation rod, insulation clamp, high voltage electroscope, etc.

Low voltage basic safety insulation; Insulated long and short gloves, hand-held tools with insulated handles, test pens, etc.

What is auxiliary safety insulation appliance? What does high voltage auxiliary safety insulation have?

Its insulation strength is not enough to assure safety and the safety appliance that has auxiliary effect to call auxiliary safety insulation appliance conversely.

High voltage auxiliary safety insulation; Long and short insulated gloves, insulated rubber boots, rubber insulated pads, insulated tables, etc.

How many kinds of electrical safety warning boards are there? How to use it?

Warning board has warning class, prohibit class, permit class, remind class four kinds.

Warning type is to warn people not to approach or touch the electric parts; The prohibition category is to prohibit the operation of a switch, to prevent people working on the line or equipment of power failure from getting electric shock; Permission classes allow workers to work somewhere; The reminder class is to remind the staff to remove the temporary grounding wire during power transmission.

Which electric tools must be installed leakage protector?

For a class of hand-held electric tools that exceed the safety voltage of 42 VOLTS, leakage protectors must be installed on all mobile electric tools and checked quarterly by the storage department.

What are the requirements for installation and use of safe pressure converter?

Step-down transformers with secondary side voltage of 36 v and below shall be powered by double-ring variable pressure gas, and the use of self-coupling step-down transformers is strictly prohibited. The transformer core, metal shell to have reliable grounding or zero. Use safety isolation transformer, that is, when there is an isolation layer between the two coils on the secondary side, the secondary side line should be insulated from the earth. Safety transformer power supply should be installed on both sides of the safety, and the use of rubber insulation flexible wire connection, the length of a side line shall not exceed 2 meters.