Brake settings
GENERAL
The brakes used by BER-MAR are electromagnetic spring brakes for dry dual braking surface. The experience gained over many years of collaboration with various industries, it allows us to claim that we have adopted the brakes respond to the latest technological standards.
The excellent quality of materials, careful construction with modern machines, production and uncompromising quality control is a guarantee of credibility and security.
This catalog contains two different series of brakes complete with accessories that are usually required (release lever, intermediate flange, clutch plate, protection ring, etc.).
Below we remember the quality of the safety spring brakes, namely: greater safety braking of the rotating masses, accuracy and positioning of the shaft at the end of the cycle.
And is possible to produce customer design motors with special brakes to best suit individual needs.
Construction characteristics
Special features are the following:
• the brake lining asbestos-free with a special steel core, ensures safe braking under extreme conditions:
Sizes 01 ÷ 06: steel ring covered with lining
Sizes 07 ÷ 10: metal disk broached with friction lining on both sides
• adjustment of the braking torque of 1.0...0.5 • M 2N
• adjustment of the air gap (patented) is done without having to disassemble the brake
• solid connecting cable
• effective protection of the surface
• insulation class B, class F on request
• CSA approved protective wire optionally prototype tested TÜV VDE 0580
• possible subsequent assembly of the release lever
• Unlimited operating time
• CE marked according to the requirements of the Low Voltage
•the disc with the brake lining with hardened surface ensures a
less wear and is protected against rust (beyond grand.06)
• IP40 - Standard, on request up to IP66
Functional characteristics
| N° | Description |
| 1 | Fixing screws DIN 912 u.6912 - 8.8 |
| 2 | Magnet |
| 3 | Armature disc |
| 4 | Adjustment ring |
| 5 | Pin |
| 5.1 | Spring |
| 6 | Hub |
| 7 | Lining |
| 8 | Friction disk |
| 9 | Spacer |
| 10 | Release lever |
Clutch plate (8) and release lever (10) are accessories.The fastening screws (1) are not included in the delivery.
The spring brake is locked with the fastening screws (1).With the screws (1) are loose you can adjust the air gap to the nominal Xn (p. 6, T1) by rotating the spacer (9). After adjusting, tighten the screws (1) and the brake is ready for work.
In the absence of voltage the armature disc (3) and the brake lining (7) are pressed against the fixing surface via the central spring (5).The lining (7) is axially free but torsionally locked by the hub (6) .The hub should instead be locked axially and torsionally.
By powering the coil of the magnet (2) creates a magnetic field that attracts the armature disc (3). Because of that the brake lining (7) is released and the shaft can rotate freely.
| Brake settings |
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Assembly instructions
| Brake settings |
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|
The brake is locked with the screws (1).With the screws loosened and in the absence of voltage the air gap is adjustable, with the help of a thickness gauge, to the nominal dimension X in the table. After adjusting, tighten the screws, the brake is ready for work.
| Air gap setting "X" | |
| From MEC 63 to MEC 90 | 0,2mm |
| From MEC 112 to MEC 160 | 0,3mm |
| MEC 180 | 0,4mm |
| Over | 0,5mm |
|
|
The wear, due to the effect of the dynamic braking, causes an increase of the air gap. Only a regular check and adjustment of the nominal air gap Xn can ensure the smooth operation of the brake. You should never have a thickness of the lining below the minimum allowable.
The distance from the mounting surface established, see B4(0.5 to 1 mm), it was calculated in consideration of any possible play of the shaft.Respecting these units will prevent the hub touches the attachment surface even in the presence of a large axial play.
The release lever may be fixed subsequently. In this case are very important the mounting dimensions m. An incorrect setting can cause a loss of braking effect, especially when the braking torque is reduced or is over-excited due to an overvoltage.
Normally, the braking torque is adjusted to the nominal torque M 2N. By turning the adjusting ring (4), (see table), the braking torque decreases. The excitation time changes accordingly.
Installing vertically brakes from 07.08.to 10.08.It can be increased by the duration of the brake at high speeds (n> 1500 min -1) using a special lining system.For further information contact our technical staff.
Grease and oil should be kept away from the friction surface.
TECHNICAL DATA
The values WRmax are valid for standard brakes and with second friction surface in cast iron. Depending on the application, these values may be higher or lower.
By using the friction disc antirust or higher speed, compared to what is specified in the diagram, considerably it reduces the work of friction permitted.
If the rated torque of the brakes is reduced, by unscrewing the adjustment ring, the friction work capacity increases.
Sizing
Decisive elements for the design of the brakes are the required braking torque, the braking time, the temperature in which they work and the hours of service.
Rated torque
To ensure that the brakes are properly sized, even in extreme conditions, the braking torque is multiplied by the safety factor.The selection of the safety factor depends on the workload of the application.
M2N = MERF x K
M2N = static rated torque [Nm]
K = safety factor > or = than 2
MERF = torque [Nm]
The dynamic torque of the double brake may be substantially lower than the rated torque.
Braking torque request
The required braking torque is the set of dynamic and static load.To apply the formula is necessary to assess whether, the load torque, it must be added
or subtracted.
MERF = MA ± ML
MA = J · a
MERF = torque [Nm]
MA = dynamic braking torque [Nm]
ML = working torque [Nm]
J = moment of inertia [Kgm2]
a= angular acceleration [s-2]
If the total moment of inertia is unknown and the driving force is constant, the
Braking torque is calculated as follows:
MERF = 9550 x P / n
MERF = torque [Nm]
P = power output [kW]
n = speed [min-1]
Working temperature
The sizing made only on the basis of the required braking torque, it is possible in a few cases.
For good sizing must also take into account the energy that develops at each braking. Decelerating the total load and the maximum moment of inertia J is reduced to the shaft to be braked (brake friction energy). The friction work capacity which depends on the braking cycles, can not be exceeded.
WR = (J x n2 / 182.5) x (M2N / M2N ± ML)
WR = work of friction [J]
J = moment of inertia [Kgm2]
n = speed [min-1]
M2N = static rated torque [Nm]
ML = working torque [Nm]
The maximum permissible friction work is valid until the corresponding speed.
In case of emergency stop at maximum speed, the friction work capacity falls considerably below the values specified in the chart.
Slip time
It is the time necessary for seeking the attainment of the rated torque.
t3 = 104.6 x (J x Dn / M2N ± ML) + t11
t3 = sleep time [ms]
J = moment of inertia [Kgm2]
n = speed [min-1]
M2N = static rated torque [Nm]
ML = working torque [Nm]
t11 = time delay coupling [ms]
Time of service
The service time depends largely on the temperature peaks during braking, which temperature is dependent on the speed, the deceleration time and the current braking torque.
For this reason it is not possible to establish a fixed time period, taking into account the different operating conditions of the machine (weight, speed).The considerations on the length of service for individual cases can be made only if you know all operating conditions.
The thickness of the lining must never be lessthan "g" min.
SWITCHING DEVICES
Switching AC side
When switching upstream rectifier on the AC side the magnetic field decays slowly. With this mode of switching the opening delay it is long enough.
The switching AC side does not need any protection system for the coil and the switching contacts. At disconnection the rectifier diodes act as free wheeling diodes.
The switching times t11 for switching AC side indicated on page 20 increase when the rectifier is connected directly to the terminal block of the motor. When the motor slows a generator voltage is applied to the motor terminals. This connection is not allowed for operation with frequency.
For line lengths of more than 10 m. between the rectifier and the brake for switching AC side, standards prescribe the use of a separate switch.
1. In this case the supply voltage can not be taken behind the motor relay
2. If it is not possible to install a further switch becomes necessary the use of special rectifiers.
Switching DC side
The commutation takes place between the rectifier and the magnet. With this mode of switching the opening delay is short, since the energy of the magnetic field is absorbed by the rectifier. The voltage spikes that occur at switching are limited to a harmless level for the rectifier.
The maximum switching frequency permitted by the DC side switching of rectifiers depends on the energy content of the magnet and is specified in Table T8 for Keb COMBISTOP. Higher switching frequencies are achieved by external connection of a varistor in parallel to the brake or the + and - DC rectifier.
Article KEB rectifier Varistor
02.91.00.90.045-2752 S20K275
04.91.00.90.045-5101 S20K510
05.91.00.90.045-6252 S20K625
06.91.00.90.045-4202 S20K420 *
* 2 components in series
Cycles and switching times
|
Switching cycles
|
|
Switching AC
|
Switching DC
|
||||||
|
Size brake
|
M2N
|
P20
|
SC1
|
SC2
|
t2
|
t11
|
t1
|
t11
|
t1
|
|
Nm
|
W
|
1/min
|
1/min
|
ms
|
ms
|
ms
|
ms
|
ms
|
|
| 00 |
1
|
11
|
70
|
140
|
35
|
60
|
100
|
12
|
25
|
| 01 |
3
|
16
|
55
|
110
|
40
|
60
|
120
|
15
|
30
|
| 02 |
4
|
20
|
60
|
120
|
40
|
40
|
90
|
10
|
20
|
| 03 |
8
|
25
|
40
|
75
|
60
|
80
|
140
|
15
|
30
|
| 04 |
16
|
30
|
40
|
75
|
100
|
140
|
200
|
20
|
50
|
| 05 |
32
|
40
|
25
|
50
|
120
|
180
|
240
|
25
|
55
|
| 06 |
60
|
52
|
5
|
10
|
240
|
200
|
330
|
25
|
90
|
| 07 |
100
|
65
|
5
|
10
|
240
|
400
|
650
|
50
|
150
|
| 08 |
150
|
75
|
5
|
10
|
300
|
700
|
900
|
60
|
180
|
| 09 |
200
|
75
|
2
|
5
|
350
|
900
|
1200
|
60
|
220
|
| 10 |
400
|
130
|
1
|
3
|
350
|
1400
|
1800
|
60
|
250
|
SC
Switching cycle maximum allowed by switching on the DC side, continuous operation and maximum operating temperature of 80 ° C.
SC1
applicable for rectifiers:
- 02.91.010-CE07
- 02.91.020-CE07
- 02.91.010-CEMV
SC2
applicable for rectifiers:
- 04.91.010-CE07
- 04.91.020-CE07
- 05.91.010-CE09
- 06.91.010-CE09
t1
Insertion time.
Time between disconnection of the power and reach of the rated torque.
t11
Response delay.
Time between the disconnection of the current and the increase of the nominal torque.
t2
Time between the connection of the current and the beginning of the decrease of the nominal torque.
t3
Scroll time.
Time between the start of the increase of the nominal torque and the achievement of the moment of synchronization.
The switching times indicated correspond to DIN VDE 580 (10.94).
