Catalogs > Safety Products Catalog > Principles, Standards and Implementation > Prevention of Unexpected Power Up
Prevention of Unexpected Power Up
| Introduction |  |
Lockout/Tagout | |
Safety Isolation Systems | |
Load Disconnects | |
Trapped Key Systems | |
Alternative Measures to Lockout | |
Trapped key systems are another method for implementing a lockout system. Many trapped key systems start with an energy isolating device. When the switch is turned off by the “primary” key, the electrical energy to the machine is removed from all the ungrounded supply conductors simultaneously. The primary key can then be removed and taken to a location where machine access is needed. Figure 117 shows an example of the most basic system, an isolating switch and a gate access lock. Various components can be added to accommodate more complex lockout arrangements.
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| Figure 117: Trapped key isolation and lockable devices |