This free, web-based, easy-to-use coordination tool makes pad-mounted under-oil transformer protection device selection effortless. By simply inputting a few pieces of data and selecting the desired level of protection, you can quickly find the right combination of Cooper Power Systems ELSP backup fuse with Bay-O-Net fuse or MagneX™ Interrupter for your application. The TransFusion Coordination Program provides you the flexibility of trying various combinations before deciding on the one that best fits your application needs. The unique program also allows for the evaluation of effects when using a specific fuse under different input conditions such as ambient temperature and preload levels. This makes it possible to optimize the final fuse selection.
When selecting low-current protection devices and backup fuses, proper fuse coordination is critical to insuring full-range transformer protection. Plotting the characteristics of each protective device using Time Current Curves (TCCs) is the ideal way to visualize proper coordination. The TransFusion™ program creates a view of the curves for each of the fuses being coordinated and the basic curves that characterize the transformer. Inputs
- Enter a transformer rating in values ranging from 5 kVA to 5000 kVA
- Enter a Primary Voltage from 2.4 to 38 kV.
- Three-phase transformers must reflect phase to phase voltage
- Single-phase transformers msut reflect phase to ground voltage
- Select the Number of Phases from the drop-down list.
- Selecting 3 Phase will allow you to adjust the Primary and Secondary connections to either Delta or Wye—default is Wye for both.
- Selecting 1 Phase will default and lock Primary and Secondary connections to Wye.
- Enter a Minimum Impedance Percentage from 1 to 10%. (Example: 2% impedance is entered as 2)
- If coordinating a 3 Phase transformer adjust the Primary and Secondary Connections to either Wye or Delta as needed. (See also, Coordinating Dual Voltage Units)
Low Current Protection
- Select a Protection Device Type. All protection device options meet inrush requirements.
- Adjust the Transformer Overload Level.
Note: The slider bar allows a check of the overload level from 4 fuses sizes. As larger fuses are selected the load allowed by the fuse increases. The transformer overload curve therefore provides input to deciding the optimal fuse of a given transformer. The ambient temperature and preload level can also be changed to study the affect of different values on the allowed overload.
Long-term Loading Criteria
- Select a Temperature Class—default is set to 65 °C.
- Adjust Ambient Temperature as needed—default is set to 35 °C.
- Adjust the Transformer Preload Percentage—default is set to 75%.
» Click "Recommendation and Charts"
Device Recommendation and Part Numbers
- The recommended Cooper Power Systems device part numbers are found on the upper right of the application screen.
- Devices may include ELSP fuse, Bay-O-Net fuse, or MagneX breaker
- Submit a Request for More Information to a Cooper Power Systems specialist. This will send your data inputs along with your contact information to Cooper Power Systems to review and respond back to you.
- Email Selection & Charts allow you to send the information to one of your colleagues to review and make recommendations prior to finallizing on a purchasing decision.
- View the coordination results using the curves and visually verify that the fuses selected meet the requirements for your application.
- Download a PDF of the Results and Curve Charts by using the link to the right of the submit button or by clicking on either the Time-Current Characterstic Curve or Transformer Overload Curve. This is an efficient method for saving your work and being able to refer back as needed.
- Email Selection & Charts allow you to send the information to one of your colleagues to review and make recommendation prior to finalizing on a purchasing decision.
This program can also be used to evaluate and recommend fuses or MagneX units for dual or tri-voltage transformers. In this case, the practice, especially for the ELSP under-oil back-up fuse, is to use the current values from the lower voltage rating and voltage rating from the higher voltage rating.Since the ELSP fuse typically is not easily changed, this allows the lowest cost for full protection. The let-through I2t and current levels will be slightly higher at the higher voltage, since a larger fuse will be called for than normally used for the higher voltage, but this generally has no significant affect on protection of the transformer.
In many cases, The Bay-O-Net links appropriate for each voltage can be specified, since the links are easily changed. For MagneX units a shunt that is incorporated into the DV switch can be used to match the effective sensor size for each voltage.
If desired, the two ELSP fuses can be used, with the DV switch bringing in the ELSP fuse appropriate for each voltage.
This same method can be used for both Delta and Wye connections, by selecting the appropriate primary and secondary connection to specify the application.