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TDR-20 - Electronic Timer with Electrical Isolation
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| The TDR-20 is a heavy duty trapped key interlock switch controlled by a fail-safe timer and solenoid. The unit is designed to control access to hazardous machines with run down times and can be used in high risk category 4 applications. The unit incorporates: a dual channel fail-safe timer; heavy duty continuously rated solenoid; solenoid position monitoring; 20A electrical switch; front panel lamp indication of solenoid position and timer failure and up to four lock centres for multiple access applications. | ||||
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| In the machine running condition the access keys are trapped and the switch contacts closed. When the machine stop sequence is initiated, a signal from the machine control circuits starts the internal timer. After a pre-set time (set to exceed the rundown time of the machine) the timer energises the solenoid and releases the access keys. Turning the primary key opens the switch contacts connected to the electrical supply or control circuits of the machine, preventing the machine from being restarted. The secondary keys can now be turned, the perimeter guard of the machine. The position of the solenoid is monitored by two safety switches. This enables an external dual channel safety relay to be connected to the two normally closed contacts of the safety switches. The safety relay will prevent the machine from being re-started in the event of solenoid failure. | ||||
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The TDR-20 is designed to operate as part of an integrated safety system, controlling access to hazardous machines. A typical example of machine isolation and access control is shown below.
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| • Solenoid (continuously rated), and timer (dual channel) controlled, key driven, force break 20 amp switch (3NO 3NC contacts). • Solenoid position monitoring (suitable for Cat 4 if supported by other safety lamps). • Complete with IP65 rated enclosure or suitable for panel mount. • Power isolation - 400MA - 20A / Motor isolation AC - 23A 7.5KW or AC-3 5.5KW • Number of safety keys to suit your application (up to 4 standard). |
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