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The electromagnetic brake of AC non-excitation run type is mounted at the back of the motor to enable the motor to stop at the same time when the power is turned off, and the load is maintained as same as before. |
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The brake of the single-phase motor is connected with the reversible motor, and the brake of the three-phase motor with the induction motor. |
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When you use a motor as a source of dynamic force, if you want to stop the motor in a short time and maintain the load at the position where it stops, the induction motor can not stop instantaneously when the power is turned off. Instead, it runs further by 30~40 rotations. On the other hand, the reversible motor makes 5~6 more rotations. (Provided to no-lead). |
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If the motor requires to be stopped instantaneously, it can use the brake pack. But the brake pack is an electronic brake circuit that can let the motor stop instantaneously but it can not hold torque. (The overrun is less than one rotation on no-load.) |
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The electromagnetic brake motor is employed if the load should be maintained. |
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The electromagnetic brake of AC non-excitation run type is mounted at the back of the motor for operation. |
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The electromagnetic motor makes 1~4 times of overrun rotation at the time the power is turned off if the electromagnetic brake motor unit is loaded. |
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The frequent instantaneous directional changes are possible from normal to reverse, and vice versa. With a simple control, it is possible to make 6 stops per minute. (However, more than 3 seconds of stoppage is required.) |
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The motor and the brake can use the same power source. The rectifying circuit is embedded in the brake and so the brake can use the same AC source as the motor uses. |
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(Fig. 1) in the right side shows a structural diagram of the electromagnetic brake motor. Our Electromagnetic Brake Motor is an RNB type, and when the coil is charged with voltage, the armature repressed by the spring is sucked in to push the spring, making a gap between the armature and the brake lining, and with release, making braking power for the motor shaft freely rotate.
This is the electromagnetic brake of AC non-excitation run type and can be connected directly to the motor. When the power source is turned off, the motor stops instantaneously and the load is maintained. The retention force is 2 kgf · cm ~ 10 kgf · cm. This type of brake is best suited if a safer brake is required when the power is turned off, because the retention force is maintained when the power turns off.
The connection can be made as shown in (Fig. 2). However, the method shown in (Fig. 3) is also possible if a simpler connection metho is sought for. In case of (Fig. 3), the braking time takes longer roughly by 50msec than that of (Fig. 2), resulting in the increase overrun. This is because the braking action lags about 50msec by the magnet even after the brake's excitation is vanished, because the magnetic energy of the motor can act on the excitation winding of the electronic brakes's magnet when the braking takes place.
| Voltage |
Size
(mm) |
Output
(w) |
Frequency
(Hz) |
Ampere
(A) |
Input
(W) |
Brake |
Torque |
| (kg.cm) |
(N.m) |
Single-phase
110V/220V |
60 |
6 |
50/60 |
0.031 |
3.1 |
2.0 |
0.20 |
|
70
|
15 |
Single-phase
110V/220V
Three-phase
220V |
80
|
25 |
50/60 |
0.054 |
5.4 |
4.0 |
0.40 |
|
90
|
40 |
50/60 |
0.100 |
10.0 |
10 |
1.00 |
| 60 |
| 90 |
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Take K8RG25NC-B as an example and let it be combined with K8G30B to drive the inertia body
(GDL2 = 1000kgf · cm2). To calculate the operating time, braking time, and overrun under the power source
frequency of 60Hz, first convert the load's inertia moment to the motor shaft as follows.
GDL2 : Fly wheel effect of load kkgf · cm2]
GDM2 : Fly wheel effect at motor shaft [kgf · cm2]
i : Ratio of gearhead
The inertia moment expressed in Sl unit can be calculated by the following expression.
g : 9,80665 [kgf · cm2]
As shown in (Fig. 5), the overrun of the motor shaft is NM ≒ 2.5 revolutions.
Hence, the gearhead's output shaft has the overrun as follows.
- As shown in (Fig. 5), the operating time t1 ≒ 130[msec], and the braking time t2 ≒ 170[msec].
- The operating time of the brake motor is a total sum of the motor's operating time and the electronic brake's
open time. Thus, if the electronic brake is left open in advance, the motor can be started quickly.
- It is advised that the bake should be open at least 10msec before the motor starts operating.
GENERAL SPECIFICATION OF INDUCTION MOTORS
| Item |
Specification |
| Insulation Resistance |
100MΩ or more when 500V megger is applied between the windings and the housing after rated motor operation under normal ambient temperature and humidity |
| Dielectric Strength |
Sufficient to withstand 1500V at 50/60Hz applied between the windings and the case after rated motor operation under normal ambient temperature and humidity for 1 min.
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| Temperature Rise |
class A (65℃) or class E (75℃)or less increase measured by thermometer after rated operation |
| Insulation Class |
Class E(120℃), UL approval motor class A (105℃)
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| Overheat Protection Device |
Built-in thermal protector (automatic return type)
:Open 130℃±5℃ Close 82℃±15℃
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| Ambient Temperature |
-10℃~40℃
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| Ambient Humidity |
85% maximum (non condensing)
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