Specifying Trip Times
You can select the method for determining trip times for this bus by choosing from the following:
- Pre-defined Fixed Times: Obtains arc clearing time for the bus from the library default values. This is not the same as the trip times calculated form the TCC curves of the upstream trip device. The values stored in the library are simply predefined approximate trip times. This is a legacy method and is not recommended.
- User-defined Times: With this option you can specify the protective device clearing time for each bus. The details of arcing time for the bus can be specified in the fields Device ID, Relay Function and Time (s). When this option is selected, a time must be specified.
- TCC Times (Automatically Calculated): Arc flash incident energy are calculated based on time characteristic current curves specified in each protective device data dialog box. The trip clearing time of the equipment where the device is a relay controlled breaker is the sum of the breaker mechanism opening time (for example, 3, 5, or 8 cycle), the relay trip time, and any time entered into the Relay Data, System, and Aux Time data fields.
- User-defined and TCC Times: Provides results for both user-defined times and TCC times as described above.
- User-defined One-line Device: With this option, you can specify which device you want to use for the TCC time, and the program will obtain the trip time automatically. You can select a device type (relay fuse, or low voltage breaker) and device ID. If you select a relay, you also select the relay function.
Note: When a user-defined time is specified and the calculation method is set to use the integrated method, only the upstream device setting is used. The time is considered as the maximum length of the simulation. See The Integrated Method for more information.
