Переведите текст на русский язык (письменно). The electric motor is a simple, robust machine which will provide power quietly and smoothly, without fumes. It is a clean source of mechanical power; it requires very little attention

Переведите текст на русский язык (письменно).

ELECTRIC MOTORS

The electric motor is a simple, robust machine which will provide power quietly and smoothly, without fumes. It is a clean source of mechanical power; it requires very little attention and can be run continuously for long periods at a constant speed and with reasonably minimum maintenance.

Electric motors can be started and stopped by the touch of a button and full power is available from the moment that the motor is started. There is no large amount of heat to be dissipated, nor is there any need to store fuel. Hence the fire risk is very low and the motor can be placed almost anywhere. Electric motors use energy only while they are running and in proportion to the work being performed.

Local environment in which electric motors are installed on farms is seldom ideal. The open frame type of electric motor is the simplest design, but it is not recommended for rural use. In some locations where there is not much dust, dirt and damp, a drip-proof frame motor may be satisfactory. But most farm motors need to be of the totally-enclosed surface-cooled type, which prevents dust and moisture from entering the windings.

Much of the electrically operated farm machinery is now supplied completely with the electrical drive by the machinery manufacturer. Though, when the choice has to be made by the farmer himself, it is important that he selects the correct motor for a particular job planned.

The standard rating of a motor (based on temperature) gives only a measure of the performance of that motor under uniform and continuous conditions and does not directly indicate the safe operating limits for fluctuating service conditions. Quite often, only the maximum load to be placed on the motor is considered and subsequently one is selected, which has a standard rating equal to this maximum load: this may lead to the equipment being over-motored with consequent loss of efficiency, coupled with a lower power factor.

Conversely, a motor may be chosen with regard to the normal running condition but neglecting conditions of overload. This choice would probably be made on economic grounds and may well result in undermotoring. Motors which run at the higher speeds, e.g. l,450 and 2,850 r.p.m. are generally more efficient and, as they are of smaller dimensions and less costly, consideration should be given, wherever possible, to their use.