Residual Risks; Selection And Labeling Of Ex-Motors - Bosch Rexroth IndraDyn A Series Project Planning Manual

13-6
Motors for Hazardous Areas

13.4 Residual Risks

Failure of the protective
equipment
Overloading
Grounding and discharge
currents
Material aging

13.5 Selection and Labeling of Ex-Motors

Selection of the motors
Labeling
If the scavenging device and the monitor for maintaining the protective
measures fail simultaneously, explosion protection in a hazardous area is
no longer ensured and a danger of explosion exists.
When the motor is overloaded, including the case where errors in the
mechanical or electrical equipment of the machine occur, high
temperatures that result in the danger of explosions can occur.
Variable-speed drive systems cause unavoidable discharge currents. If
the grounded connector in the motor cable and the second separate
grounded connector on the motor housing are not connected as specified
or are interrupted by corrosion or other defects during their lifetime, the
discharge current flows (as leakage current) over conducting housing
parts, resulting in the dangers of sparking at joints and, if explosive
materials are present, explosions. Therefore, check the proper conditions
of both grounded conductors in regular intervals.
The periods of action and penetration of explosive materials depend on
the application. They depend on the aging of the seals, the mechanical
design of the motor, the characteristics of the explosive materials and the
average temperature that occurs during the operating time as a
consequence of the load cycles.
If an Ex version of a motor is required, the motor must be selected and
ordered on the basis of a predefined encoder type in the respective motor
type code.
Ex motors are defined by way of selecting the encoder option
• M6
• S6
in the motor type code.
Accordingly, the figure 6 on the 18
explosion-protected motor. This applies to the following motors:
• MAD1□□□-□□□□-□□-□6-□□□-□□-□□
• MAF1□□□-□□□□-□□-□6-□□□-□□-□□
IndraDyn A motors in EX design have an additional label that is located
on the side of the motor housing, next to the motor type label. It shows:
• the classification of the motor according to ATEX
• important details for adjusting the motor scavenging device.
Rexroth IndraDyn A
th
position of the type code signifies an
DOK-MOTOR*-MAD/MAF****-PR03-EN-P