Motor increased safety

Slipring induction motor, increased safety, flameproof slipring enclosure, flameproof standstill heaters, terminal boxes in increased safety ... 

Rotating electrical machines starting performance of single-speed three-phase cage induction motors for voltages up to and including 690 V Electrical apparatus for explosive gas atmosphere. Increased safety protection e 8789/1996 6381/1991 BS EN 60034-12/1996 BS 5501-6/1977... 

This is a location safer than Zone I with a likelihood of concentration of explosive gases, chemical vapour or volatile liquids during processing, storage or handling. This would become a fire hazard only under abnormal conditions, such as a leakage or a burst of joints or pipelines etc. Such a condition may exist only for a short period. A standard motor with additional features, as di.scussed below, may also be safe for such locations. A non-sparking type. Ex. n , or an increased safety motor, type Ex. e , may also be chosen for such locations. 

Special-purpose motors such as increased safety motors, flame-proof or explosion-proof motoi s must be checked for gaps, clearances and creepage distances of all the mating parts forming flame paths. The construction of these motors must follow lEC 60079 as noted in the list of standards. 

Electrical apparatus for explosive gas atmospheres. Increased safety motors. General requirements 6181/1991 BS 5501-6/1977 -... 

High power cage induction motor, pressurized, terminal box in increased safety, standstill heaters in flameproof enclosures ... 

The first main feature of increased safety is the reduction of operational temperatures for (organic) insulating materials in order to achieve a higher lifetime in service and to reduce the probability of an early breakdown of the insulation in the windings of motors, generators, transformers (and inductances). 

Asynchronous motors (squirrel cage induction motors, the rotor-stator part of slipring induction motors) and the rotor-stator part of synchronous motors are within the scope of increased safety due to the omission of sparks and arcs assuming an appropriate construction of rotor and windings. Tire standards IEC 60079-7 and EN 50019 contain mechanical and thermal requirements that follow this aim. 

The fact that all internal parts of a motor in increased safety shall comply with the temperature limitations according to the temperature class, results in somewhat uneconomical motor dimensions for classes T4, T5 and T6, or, in other words, the rated power is considerably reduced (Table 6.22) compared with normal industrial design. ... 

Compared with rotating machines in increased safety - e there are no additional requirements for the windings or for the gap between stator core and rotor. The interior of flameproof motors and generators is identical... 

Figure 6.97 Flameproof brake motor, totally enclosed, non-ventilated. Motor and brake housing flameproof, terminal compartments according to increased safety. Motor ...

Type of protection EEx de IIC Rated voltage 690 V 3AC Rated frequency 50/60 cps Rated current 0.1 A. .. 22.5 A, depending on motor current range Enclosure material plastics Terminals according to increased safety - e... 

An increased motor speed (at a higher frequency) may cause an increased explosion pressure in a flameproof enclosure (see Section 8.1). Bearings may show an increased temperature and exceed the temperature class of the motor where fitted outside the flameproof enclosure (Fig. 6.85(b)). In terminal compartments according to increased safety - e clearances and creepage distances at an increased voltage may not comply with the requirements... 

Historically, the bulk of urethanes and other plastics have been for interior seating and trim and for mechanical and electrical parts. With its first use in 1970, SMC was the major plastic used on the outside of the car. The promulgation of the Motor Vehicle Safety Standard 215, the bumper standard, resulted in an increase in the external uses of urethanes and other plastics. This resulted in the use of various types of elastomers for bumper sight shields, fender extenders and fascia. 

Type e is also called increased safety and intended for apparatus that is to be installed in a Zone 1 area. Two of the allowable features of the type d enclosures, namely permitting sparking components and no Temperature Class hmit to the internal components, cannot be incorporated into the type e designs. The practical aspect of this is the removal of a source of ignition i.e. a spark or a hot surface. In many types of equipment e.g. luminaries, terminal boxes, junction boxes, some designs of motor control stations, telephones and public address speakers, the elimination of these two sources of ignition is not a difficult problem. 

Increased safety e (note 1) EN 60079-7 Additional technical measures are implemented in order to prevent with high reliability the possibility of impermissibly high temperatures, sparks and electric arcs inside or outside of an equipment, which do not occur during normal operation. Terminal and junction boxes, control boxes for accommodating Ex devices (which are protected according to a different types of ignition protection), squirrel cage motors, lamps, installation materials, inductive ballasts, transformers... 

Develop and implement comprehensive motor carrier safety and loss control program. Conduct and monitor accident reporting and investigation. Inspect facilities, equipment, and property for existing or potentially hazardous conditions. Recommend corrective/preventive measures to reduce risk. Analyze and update safety policies, procedures, and plans to promote a safe working environment and increase safety awareness. Identifies, monitors, evaluates, and tracks all safety activities through audits and statistical analysis. 

Safety starts with gaining control over the daily activities and work processes of your operation. And that s exactly the main purpose of written motor carrier safety policies — to gain control over, and increase overall, company safety. 

Type e equipment, also known as increased safety equipment, employs a protection method to electrical apparatus that does not, in normal operation, produce sparks. Examples are transformers and squirrel cage motors. Type e equipment may be used in Zone 1 areas. 

If safety programs have stalled on a plateau of acceptance, professionals should zero in on the causes of most work fatalities motor vehicle safety, truck fleet safety, workplace violence prevention, and fire and explosion protection (fatal work injuries resulting from fires and explosions rose from 113 in 2009 to 187 in 2010, an increase of 65 percent, according to the BLS. 

---