New India Brake Motors are offered for various applications requiring almost instantaneous stopping of the driven load. These motors are offered in frame sizes 63 to 225m. their operations is of 'fail safe' type. i.e. the brake is applied, when, power to the motor is switched off, or, if power failure occurs.

Construction

A Brake Motor is an integral combination of an A.C. induction motor and a disc type, fail safe, electromagnetic brake unit. It consists of the following:

• A.C.Induction motor
• Encapsulated brake coil housed in the non-driving end End-shield.
• Brake liner attached to the armature disc at its interface with the cooling fan
• Cooling fan.
• The rectifier unit is provided inside the Terminal Box. It converts A.C. supply into D.C supply for Brake coils.

Operation

Under no power condition Brake springs keep the Brake Liner pressed against the cooling fan. This prevents rotor shaft rotation, because, the fan is keyed to it. When power is switched on, the Brake coil gets energised by the Rectifier unit. It instantly attracts armature disc by overcoming the spring force. This action results in releasing of the fan allowing the rotor to rotate freely. When power fails or when it is switched off, the Brake coil gets de-energised. This results in the spring pressing the brake liner against cooling fan by returning armature disc to its original position. This causes almost instantaneous braking of rotor. Fail safe condition is thus ensured.

For applications, where total load stopping time is not very critical, A.C. side interruption can be used. However, for applications, where faster braking is required, D.C. side interruption should be used. This entails additional contactors interlocking with main contactor.

Special Features

• Being simple and rugged-in construction, these motors need very little maintenance. In the rare events of failure, repair is simple and easy
• No seperate D.C supply is necessary for brake coil energisation, because a rectifier unit is provided. The rectifier is open type and fixed between the two terminals inside the terminal box. Being open type, it ensures good heat dissipation and is very easy to replace.
• Special barke liner is used, which ensures that the braking torque value remains quite stable throught the use. Compensation for liner wear is easily done by advancing the positon of the fan by tightening the castle nut at the non-drive end. The desig of Brake motr facilitates a very easy replacement of armature disc and brake linear assembly.
• Since the fan serves as a braking surface (unlike some other designs). It also serves to cool the Brake coil and the motor. These Brake Motors being fan-cooled are availbale in smaller frame sizes than other brake motors which are surface-cooled. Therfore, these motors are more compact and economical for a given application.
• For crane and hoist duty applications Brake Motors are offered with special rotors. These rotors are specially suited for S3 and S4 duty normally encountered in hoist and rane applications.
• We also provide special tailor made mouting with splinded o/p shaft.

Applications

Brake Motor are used for numerous applications.A few of them are listed below:

• Cement concrete batching plants
• Packing Machine
• Textile Machinery
• Machine Tools
• Printing Machines
• Cranes and Hoists
• Material Handling Equipments
• Leather Processing Machines
• Geared Motors
• Cable Reeling Drums
• Rolling Mills
• For all application where stopping & positioning is required and or also forward and reversal of direction is required.

Enquiry Details

When placing an enquiry kindly furnish the following information:

1. Application details
2. Output and speed
3. Duty cycle with number of starts/stops per hour
4. Ambient temperature and special environmental factors likely to affect the motos, if any.
5. Method of mounting
6. Load GD² referred to motor shaft
7. Braking torque required*
8. Maximum permissible stopping time
9. Any other special features required

* These are inter-rlated parameters and related by following formula:

Where,

T = braking torque in kgm.
GD² = load GD² + rotor GD²
N= speed fo rotation in r.p.m
t_app = brake application time (to be obtained from Table 1)
T_s = total stopping tune

Specifications of Brake Motors : (3 Phase, 415+6% volts, 50 + 3% Hz)

1. Other braking torque values can be considered for special applications.

2. Other outputs can be offered on request where feasible.

* Brake release time:
The time interval between the instant supply to the brake coil is switche on, to the instant
The brake is released.

** Brake application time:
The time interval between the instant supply to the brake coil is interrupted to the instant the brake is applied. The value depends on weather the circuit is interrupted on AC side or DC side. For performance details, please refer Standard Motor Catalogue.

Maximum allowable Load

The value given refer to a bearing life of 20,000 working hours. A pulley other than those recommended in above table have to be selected in such a way, as not to excedd the value 'X' and 'P' in the above table. For other specific problems consult us. Pulley load can be calculated from the following formula:

Where,

a= Belt factor 2 for vee belt 3 for flat belt
N= output for the motor in kw
n= speed for the motor in rev/min
D= Pulley dia. in mt.
W= weight of the pulley in kg.

Note: Details of Motors in 160 M to 225M will be made available upon request as these motors are normally made to customers specifications.