| Home > Trapped Key Interlocks > Mechanical Bolt Interlocks > BEMF/MSI - Movement Sensing Interlock |
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| Description |
| Both the ‘BEMF’ and the ‘MSI’ units are designed to control access to machinery that has a run-down time. The ‘BEMF’ unit relies on the measurement of the electromotive force generated by the windings of an electric motor. Only when the motor has stopped will the emf drop to zero and allow the release of a key. The unit is suitable for connection to AC and DC motors including DC braking systems. The ‘MSI’ relies on the detection of motion via two sensors, only when both sensors detect zero movement will a key be released. Both units are suitable for category 4 safety applications. The BEMF and MSI have been designed to provide the highest level of safety when installed as part of an access control system for dangerous machinery. A typical example of machine isolation using the BEMF is shown below. |
| Operation |
| When the electric motor that is driving the protected piece of machinery is running, the key of the BEMF unit cannot be removed, hence preventing access to the hazardous area. To release the key and gain access to the area, the electrical motor must be switched off. The key will remain trapped whilst the motor remains in motion, only being released when the motor has coasted to a stop, this ensures that no access can be gained during a run down time, even if the piece of equipment has a variable run down. The key released can then be used to unlock the AI access lock. |
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| System Description |
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| Features |
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Suitable for variable run-down machinery.
Single / three phase or DC motor control.
Category 4 and category 2 versions available.
Complete with IP65 rated enclosure.
Switch apparatus - IEC947-13 IEC947-5 BS N60947.
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| Order Information |
| Part # |
Description |
| 0243 |
BEMF - Movement Sensing Interlock |
| 2244 |
MSI - Movement Sensing Interlock |
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