Bharat Bijlee Motors

Brake Motors

Brake Motors

Type MB 0.25 kW - 9.3 kW Frame - 71-132M

BBL manufactures TEFC three phase DC Brake Motors with Type 'MB'. These motors are used for applications requiring positive and instantaneous braking. These motors are 'fail safe', which means that the brake will be applied immediately in case the power supply fails or is switched off.

These motors have a built in rectifier along with a varistor for protecting the rectifier as well as the brake coil from voltage surges. The special brake liner used assures consistent braking torque with minimum wear. This leads to almost maintenance free operation. These motors can be offered in various types of mounting. BBL manufactures these motors in frame sizes from 71 to 132M in 2, 4, 6 and 8 pole.

Multi speed brake motors can also be supplied. Motors from 90S to 132M can also be supplied with a manual release arrangement to manually release the brake.

Brake motors are offered for various application requiring almost instantaneous stopping if driven with load. These motors are offered in frame size 71 to 132. Their operation is of “fail safe” type, i.e., the brake applied when, power to the motor is switched off, or, if power failure occurs.

Enclosures: (Material & T-Box location)

Frame Sizes Enclosure Materials Terminal Box Location
Standard Option Available
71-80 Aluminum Top LHS
90S-132M Cast Iron RHS TOP

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 following:
I) A.C. induction motor.
II) Encapsulated brake coil housed in the non driving side end-cover.
III) Brake liner attached to the armature disc at its interface with the cooling fan.
IV) Cooling fan.
V) The rectifier unit is provided inside the terminal box. It converts A.C. supply into D.C. supply for the brake coil.

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 energized through the Rectifier unit. It instantly attracts the armature disc by overcoming the spring force. This action results in releasing of the fan allowing the rotor to rotate freely. When the power fails or when it is switched off, the brake coil gets de-energized. This results in the springs pressing the brake liner against cooling fan, i.e. 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 application where faster braking is required, D.C. side interruption should be used. An additional contactor interlocked with main contactor should be used.

Special Features a. Being simple and rugged in construction these motors need very little maintenance.
b. No separate DC 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 terminals box. Being open type, it ensures good heat dissipation and is very easy to replace. Varistor is provided across the DC terminals to protect the brake coil and rectifier against line and switching surges.
c. Special brake liner is used, which ensures that, the braking torque value remains quite stable throughout the use. Compensation for liner wear is done by advancing the position of the fan by tightening the castle nut at the non-drive end. The design of brake motor facilitates a very easy replacement of armature disc and brake liner assembly.
d. 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 available in smaller frame size than other Brake motors which are surface cooled. Therefore, these motor are more compact and economical for a given application.
e. For Crane and Hoist duty application Brake motors are offered with special rotors to suit their respective duties. These rotors are specially suited for S3 and S4 duty normally encountered in Crane and Hoist application. f. Mechanical manual release of the brake as an optional feature is available from 90 to 132 frames. In case of power failure, the brake can be released manually with a lever.
g. The working of the rectifier unit has been successfully type tested for one million operations. Frame Sizes Enclosure Materials Terminal Box Location Standard Option Available 71-80 Aluminum Top --- 90S-132M Cast Iron RHS LHS TOP TECHNICABRLA KIEN MOFTOORSR MATION 25


Brake Moter

DC Brake Moter

Brake Motors Type MB Foot Mounted (B3) TEFC Series Frame 71-132M

Brake Motors Type MB Flange Mounted (B5) TEFC Series Frame 71-132M 71-132M

rake Motors Type MB Face Mounted (B14) TEFC Series Frame 71-132M