CAPE FAQs

Got questions...?

Q: What arc flash calculations does CAPE provide?

A: CAPE’s Arc Flash macros in the System Simulator module determine the worst product of fault current "I" and fault clearing time "t.” CAPE computes the clearing time based on the response of the protective devices around the fault location, which is basically a stepped-event analysis. Thus, a fault might need multiple breaker openings before it is actually cleared.

In a radial system, there is probably only one device that will operate to clear the fault. But in a network, multiple breaker openings might be needed.

The CAPE macros apply a user-specified fault at a large number of locations in the network: at buses, sliding faults on lines to determine the clearing time. For each network component, the largest I x t product is determined to be the worst-case arcing scenario.

The macros output this information into a text file. You can use this text file output to calculate the incident energy and the arc flash boundary outside of CAPE.

However, we have been hearing from other CAPE users that they would like CAPE to calculate the incident energy and arc flash boundary, without going outside CAPE to use another spreadsheet or program.

Therefore, we are in the process of developing a macro that does this. It is almost complete for the case where the system voltage is 15kV or less (as described in the IEEE 1584 guide). If you would like more information about this topic, please contact us.

Q: What are the primary advantages of CAPE?

A: These are some of the big advantages of CAPE:

  • Its superior data structures handle real-life configurations very well, including complex mutual coupling.
  • Its true database foundation that allows the raw Line Constants data and network model to be integrated with data used for other functions, eliminating errors and minimizing data entry.
  • Its thorough error-checking, which meets rigorous protection engineering standards.
  • Its use of graphics to help in data verification and facilitate more intuitive analysis.
  • Its vast library of detailed relay, recloser, and fuse models specific to the manufacturer’s products.

Q: Is CAPE mainly designed for utilities (power generation, transmission & distribution) or industrial applications (small generation, distribution and lots of motor loads) ?

A: CAPE is designed for utility transmission and distribution systems. However, it models the relays, distribution reclosers, fuses, and LV circuit breakers that are also used in industrial systems. Moreover, CAPE supports the modeling of elaborate bus structures.

Q: Does CAPE have any limitation on the number of buses, transformers, etc.?

A: There is no size limitation on a CAPE model. The program dimensions itself based on the size of the network it reads in the attached database.

Q: Is CAPE able to solve cases for Power Plant Generation Auxiliary Systems and Medium and Low Voltage Systems?

A: Yes. For example, we recently built a network for a customer who is modeling part of a very large coal-fired power plant; it goes down to around 400V from 110 kV. In this case, we used a double-bus with a spare bus/breaker for part of the model. This particular plant model was added to a 3,500-bus system model in such a way that the user can switch in the detailed plant model or revert to the original simplified model any time.

Q: Can CAPE generate non-ideal power swing trajectories?

A: Yes, using the Coordination Graphics module.

Q: Can CAPE software be used for transient stability study, dynamic simulation and including motor start-up/run up study?

A: CAPE is a phasor-based domain. It does not perform transient stability analyses. However, it does do motor starting computations quite comprehensively. We have available on request a CAPE document on induction motor modeling and motor starting under various starting circuits.

Q: Does CAPE have the ability to calculate impedances of underground transmission cables?

A: CAPE does not have a cable constants module, but it does have a macro that does some calculation of cable constants. To use it, you need to have a set of tables available to you. If you don’t have the tables, let us know and we can direct you.

Q: Does the software come with a protection relay library, and does Electrocon provide technical support when we need a new protection relay model?

A: Yes, CAPE comes with a large master library of relays, reclosers, fuses, and conductors. Our protection models are detailed and reliable. We model devices by manufacturer and style, and use the actual manufacturer-named settings in those models. Models include distance, voltage, and current differential relays, not just overcurrent relays. For overcurrent relays, we model voltage-restrained and product type time-overcurrent elements as well as standard OC elements. All required data reside in the user's single database, and that includes the network, protection system, and the data required for line constants calculations.

There are close to 6,000 relay styles in the CAPE library now. If your relay is not already modeled, let us know and we will add the ones you need, as long as the manufacturer's instruction manual for the device is available. This includes the modeling of special TOC curves. We will always provide technical support to customers on maintenance, often going beyond the routine level of support.

Q: Why do you say that CAPE models can predict misoperations?

A: A customer coordination study predicted misoperation of a Zone 1 ground distance element that was caused by a shortcoming in the manufacturer's design. An actual misoperation occurred a few weeks later.

The System Simulator and Relay Checking functions are very powerful tools for finding miscoordinations automatically, but they are not required for basic work with CAPE.

Q: Does CAPE have a working customer group where we can share the library data?

A: We have a users group and an online forum where you can exchange questions and ideas with other users. But Electrocon takes responsibility for maintaining the library of protective device models and making them available to customers. There is no charge for this so long as the user's company is active on CAPE maintenance. Maintenance service is included with the license fee for the first year.

Q: Can I share a CAPE database on a local area network? How should that be set up?

A: The DBMS must be installed on the same PC where an accessible database is placed.  This may be any PC in the network, including a traditional file server. Any machine can be used as the server, so long as it is accessible from the desired client machines and has TCP port 3050 open.

Q: Can the CAPE data be imported from and exported to other software?

A: Yes, the CAPE network data can be exported in formats including Siemens PSSE and ASPEN..

Q: I am looking for a software package to calculate mutual impedance between two or more three-phase circuits running in parallel. Does CAPE do that?

A: CAPE Line Constants calculates mutual impedance as you describe. LC is especially convenient for computing mutual coupling in complicated rights-of-way with many lines. A pdf file of the LC tutorial/reference manual is available on request. Session 3 of this manual gives a very good example of complex rights-of-way that the line-constants program can model. There is no restriction on the number of tower strings that you can have in a right-of-way.

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