Seepex BN 5-12 Series, Operation & Maintenance Manual

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Manual of Electric Motors 98
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Motors fitted with cylindrical roller bearings require a minimum radial load to ensure a normal operation.
For information regarding the radial preload, please contact WEG.
7.2.1.Limits of vibration
The vibration severity is the maximum vibration value measured at all positions and in all directions as
recommended in the standard IEC 60034-14. Table 7.5 specifies the limits of the maximum vibrations
magnitudes according to standard IEC 60034-14 for shaft heights IEC 56 to 400, for vibrations grades A and B.
The vibration severity limits in Table 7.5 are given as RMS values (Root Mean Square values or effective values)
of the vibration speed in mm/s measured in free suspension condition.
Motors fitted with oil mist lubrication systems can be operated continuously for a maximum of one hour after
the failure of the oil pumping system.
Considering the sun’s heat increases the operating temperature, externally mounted motors should always be
protected from direct sunlight exposure.
Each and every deviation from the normal operating condition (tripping of the thermal protection, noise and
vibration level increase, temperature and current rise) should be investigated and corrected by WEG Authorized
Service Centers.
According to NEMA MG 1, the allowed vibration limit for standard motors is 0.15 in/s (peak vibration in in/s).
Table 7.4 - Minimum required water flow and the maximum allowed
temperature rise of the cooling water after circulating through the motor
Table 7.5 - Recommended limits for the vibration severity according to standard IEC 60034-14
Frame size
Flow rate
(litres/minute)
Maximum allowed water
temperature rise (°C)
IEC NEMA
180 284/6 12 5
200 324/6 12 5
225 364/5 12 5
250 404/5 12 5
280
444/5
445/7
447/9
15 6
315 504/5 16 6
355
586/7
588/9
25 6
Shaft height [mm] 56 < H < 132 132 < H < 280 H > 280
Vibration grade Vibration severity on elastic base [mm/s RMS]
A 1.6 2.2 2.8
B 0.7 1.1 1.8
Notes :
1 - The values in Table 7.5 are valid for measurements carried out with decoupled machines (without load) operated at rated voltage and
frequency.
2 - The values in Table 7.5 are valid regardless of the direction of rotation of the machine.
3 - The values in Table 7.5 are not applicable to single-phase motors, three-phase motors powered by a single-phase system or to
machines mounted in situ or coupled with inertia flywheels or to loads.
Note :
For the load operation condition, the use of the standard ISO 10816-3 is recommended for evaluating the motor vibration limits. In the
load condition the motor vibration will be influenced by several factors, such as, type of the coupled load, condition of the motor fixation,
alignment condition under load, structure or base vibration due to other equipments, etc..
g
NEMA MG 1 Part 12. The motor has been designed to be operated in one of the following variations:
g
±10% of the rated voltage, with rated frequency;
g
±5% of the rated frequency, with rated voltage;
g
A combined variation in voltage and frequency of ±10%, provided the frequency variation does not exceed
±5%.
If the motor is cooled by ambient air, clean the air inlet and outlet openings and cooling fins at regular intervals
to ensure a free airflow over the frame surface. The hot air should never be returned to the motor. The cooling
air must be at room temperature limited to the temperature range indicated on the motor nameplate (if no room
temperature is specified, please consider a temperature range between -20 °C and +40 °C).
Table 7.4 shows the minimum required water flow for water cooled motors considering the different frame sizes
and the maximum allowed temperature rise of the cooling water after circulating through the motor. The inlet
water temperature should not exceed 40 °C.
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