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Section 2. Electrical equipment and electrical installations for general purposes

Chapter 2.5. Electric motors

Encyclopedia of radio electronics and electrical engineering / Rules for the technical operation of consumer electrical installations (PTE)

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2.5.1. This chapter applies to AC and DC motors.

2.5.2. Electric motors, ballasts and protections, as well as all electrical and auxiliary equipment for them, are selected and installed in accordance with the requirements of the rules for electrical installations.

2.5.3. Electric motors and the mechanisms driven by them must be marked with arrows indicating the direction of rotation.

On electric motors and ballasts there must be inscriptions with the name of the unit and (or) mechanism to which they relate.

2.5.4. Fusible fuse links must be calibrated and have a stamp indicating the rated current of the setting, applied at the manufacturer or subdivision of the Consumer, who has the appropriate equipment and the right to calibrate the fuses. The use of uncalibrated inserts is not allowed.

2.5.5. In the event of a short interruption in the power supply of the electric motors, self-starting of the electric motors of the responsible mechanisms must be provided upon re-applying voltage to keep the mechanisms in operation according to the conditions of the technological process and admissibility under safety conditions.

The list of responsible mechanisms involved in self-launching must be approved by the technical manager of the Consumer.

2.5.6. Purged electric motors installed in dusty and damp rooms must be equipped with devices for supplying clean cooling air, the temperature and quantity of which must comply with the requirements of the factory instructions.

The density of the cooling path (motor housing, air ducts, dampers) must be checked at least once a year.

2.5.7. Electric motors with water cooling of the active steel of the stator and rotor winding, as well as with built-in water air coolers, must be equipped with devices that signal the presence of water in the housing. Operation of equipment and apparatus of water cooling systems, water quality must comply with the requirements of factory instructions.

2.5.8. On electric motors with forced lubrication of bearings, protection must be installed that acts on the signal and shutdown of the electric motor when the temperature of the bearing shells rises or the supply of lubrication stops.

2.5.9. The voltage on the switchgear busbars must be maintained within (100 ¸ 105)% of the nominal value. To ensure the durability of electric motors, it is not recommended to use them at voltages above 110 and below 90% of the nominal.

When changing the frequency of the supply network within ± 2,5% of the nominal value, operation of electric motors with rated power is allowed.

The rated power of electric motors must be maintained with a simultaneous voltage deviation of up to ± 10% and frequency of up to ± 2,5% of the rated values, provided that when operating with increased voltage and reduced frequency or with reduced voltage and increased frequency, the sum of the absolute values ​​​​of voltage and frequency deviations does not exceeds 10%.

2.5.10. On group assemblies and shields of electric motors, voltmeters or signal lamps for monitoring the presence of voltage must be provided.

2.5.11. Electric motors of mechanisms, the technological process of which is regulated by the stator current, as well as mechanisms subject to technological overload, must be equipped with ammeters installed on the starting board or panel. Ammeters must also be included in the excitation circuits of synchronous motors. On the ammeter scale there should be a red line corresponding to the long-term permissible or nominal value of the stator (rotor) current.

On DC motors used to drive critical mechanisms, regardless of their power, the armature current must be controlled.

2.5.12. Electric motors with squirrel-cage rotors are allowed to be started from a cold state 2 times in a row, from a hot state - 1 time, if the factory instruction does not allow more starts. Subsequent starts are allowed after the motor has cooled down for a period of time determined by the manufacturer's instructions for this type of motor.

Repeated switching on of electric motors in case of disconnection by their main protections is allowed after examination and control measurements of insulation resistance.

For electric motors of critical mechanisms that do not have a reserve, one repeated switching on after the operation of the main protections is allowed based on the results of an external examination of the motor.

Re-starting of electric motors in the event of backup protections is not allowed until the cause of the shutdown is clarified.

2.5.13. Electric motors that are in standby for a long time must be constantly ready for immediate start-up; they must be periodically inspected and tested together with the mechanisms according to a schedule approved by the technical manager of the Consumer. At the same time, for outdoor motors that do not have heating, the insulation resistance of the stator winding and the absorption coefficient should be checked.

2.5.14. The vertical and transverse vibration components (r.m.s. value of vibration velocity or twice the amplitude of oscillation) measured on the bearings of electric motors articulated with the mechanisms must not exceed the values ​​\uXNUMXb\uXNUMXbspecified in the factory instructions.

In the absence of such instructions in the technical documentation, the vibration of the bearings of electric motors articulated with mechanisms should not exceed the following values:

It is allowed to operate units with increased vibration of the bearings of electric motors articulated with mechanisms operating in difficult conditions, in which rotating working parts wear out quickly, as well as electric motors whose service life exceeds 15 years, for the time necessary to eliminate the cause of increased vibration. Vibration standards for these conditions should not exceed the following values:

The frequency of vibration measurement of the bearings of electric motors of critical mechanisms must be established by a schedule approved by the technical manager of the Consumer.

2.5.15. Control over the load of electric motors, brush apparatus, vibration, temperature of the elements and cooling media of the electric motor (windings and cores of the stator, air, bearings, etc.), care of bearings (maintaining the required oil level) and devices for supplying cooling air, water to air coolers and windings, as well as the operation of starting and stopping the electric motor must be carried out by the personnel of the unit servicing the mechanism.

2.5.16. Electric motors must be immediately disconnected from the network in the following cases:

The operating instructions may also indicate other cases in which the electric motors must be immediately turned off, as well as the procedure for eliminating the emergency condition and starting the electric motors.

2.5.17. Preventive testing and repair of electric motors, their removal and installation during repair must be carried out by trained personnel of the Consumer or the contractor.

2.5.18. The frequency of major and current repairs of electric motors is determined by the technical manager of the Consumer. As a rule, repairs of electric motors should be carried out simultaneously with the repair of drive mechanisms.

2.5.19. Preventive tests and measurements on electric motors must be carried out in accordance with the rules for testing electrical equipment (Appendix 3).

See other articles Section Rules for the technical operation of consumer electrical installations (PTE).

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