8 central vacuum motor FAQ answered by Ametek


Ametek Lamb has answers to your 8 most frequently ask question about central vacuum motors.

1. How many times can brushes be changed and what life can be expected from each change?
Original brush life on Lamb produced vacuum motors will vary considerably from one application to another. Brushes can normally be changed two times before armature and other component replacement is required. On the first brush change you can expect up to 60% of the original life. On the second change, you should receive up to 40% of the original life. After the second change, the commutator is normally worn to the point where further brush replacement is not possible. This applies if brushes are changed before the brush shunt is fully extended. If this is allowed to happen the contact between the brush and the commutator surface will be disturbed, resulting in pitting and other damage tot he commutator surface. Should a commutator be damaged, it should be turned or replaced before the brushes are replaced.

2. When brushes are changed, what is the proper run-in procedure?
To achieve the best performance the brushes should be seated on the commutator before full voltage is applied. After brush change apply 50% to 75% voltage for 30 minutes to accomplish this seating. The motor will return to full performance after an additional 30 to 45 minutes running period at full voltage. Direct application of full voltage after changing brushes will cause arching, commutator pitting and reduce overall life.

3. Will 115V, 60 cycle motors operate from 115V, 50 Cycle input?
Yes. The vacuum motors considered here will operate from 25-60 cycle, A.C. or on D.C.

4. What happens when two or more motors are connected in (air) series?
In this arrangement involving bypass motors, the working air exhaust from the first motor is directed to the fan intake of the second motor, providing for a significant increase in the vacuum performance at small orifice conditions with no appreciable increase in CFM. We don not recommend the used of two through-flow motors in a series connection as the heat from one motor is transferred to the second motors creating an overheated situation.

5. What happens when two or more motors are in (air) parallel?
This arrangement usually involves two or more motors mounted in the cover of a large container. Each motor’s fan system is working from the same air space. In this case, air flow (CFM) is significantly increased at a large orifice conditions with no appreciable increase in vacuum.

6. Can 230V motors be operated at 115V?
Yes, on motors of this type, it is usually beneficial from a life standpoint to operate at less than rated voltage. Air performance will, of course, drop off rapidly as you pull back from rated input.

7. What effect does motor speed have on brush life?
Generally speaking, brush life through a direct voltage reduction is tripled by cutting the motor speed in half.

8. What is the relationship of the air watt value to vacuum performance? 
The air watt or air power term is a useful description regarding the actual cleaning potential available as a result of air movement (vacuum and airflow) in a vacuum cleaner. This rating could be used in terms of a cleanability rating.

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