Fault
A Fault object is a resistor network that can be configured in a variety of ways. It is nominally designed with the same connection philosophy as the Capacitor. That is, it is a two-terminal device in which the second terminal defaults to ground. This is often what is desired when simulating a fault for short-circuit studies. However, the OpenDSS Fault object may be configured to do much more and can be configured to represent any type of fault. For example, it can be connected between transmission overbuild and distribution underbuild to simulate the transmission falling on the distribution circuit.
A Fault object is a standard linear Power Delivery component, completely defined by its primitive admittance matrix. You can have as many Fault objects on the circuit as you wish (some may cause the power flow solution to diverge – if so, switch to a direct solution or a dynamic solution). For Monte Carlo fault mode (MF) you will distribute Fault objects all over the circuit is some proportion. The solver will enable one at a time for each solution.
Since the Fault object is nothing more than a resistor network, you may use it for purposes other than modeling short circuit faults – anything that requires a resistor model. With the Gmatrix property a very complex resistive network can be modeled. For example, you may wish to represent a fault that has one resistance L-L and another L-ground. Note that it is specified as a nodal conductance matrix.
In time mode simulations such as Dynamics, the initiation of the fault can be delayed (ONtime property) and it will automatically clear itself when the current drops below a certain level (MinAmps property) if the fault is declared to be Temporary.
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phases |
Number of Phases. Default is 1. |
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bus1 |
Name of first bus. Examples: |
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bus2 |
Name of 2nd bus. Defaults to all phases connected to first bus, node 0, if not specified. (Shunt Wye to ground connection) |
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R |
Resistance, each phase, ohms. Default is 0.0001. Assumed to be Mean value if gaussian random mode.Max value if uniform mode. A Fault is actually a series resistance that defaults to a wye connection to ground on the second terminal. You may reconnect the 2nd terminal to achieve whatever connection. Use the Gmatrix property to specify an arbitrary conductance matrix. |
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Gmatrix |
Use this to specify a nodal conductance (G) matrix to represent some arbitrary resistance network. Specify in lower triangle form as usual for DSS matrices. |
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MinAmps |
Minimum amps that can sustain a temporary fault. Default is 5. |
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ONtime |
Time (sec) at which the fault is established for time varying simulations. Default is 0.0 (on at the beginning of the simulation) |
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pctperm |
Percent of failures that become permanent. (not currently used) |
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Temporary |
{Yes | No} Default is No. Designate whether the fault is temporary. For Time-varying simulations, the fault will be removed if the current through the fault drops below the MINAMPS criteria. |
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%stddev |
Percent standard deviation in resistance to assume for Monte Carlo fault (MF) solution mode for GAUSSIAN distribution. Default is 0 (no variation from mean). |
Standard Inherited Properties (may not apply to all Fault elements)
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normamps |
Normal rated current. |
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emergamps |
Maximum current. |
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basefreq |
Base Frequency for ratings. |
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faultrate |
No. of failures per year. This property can be used by such things as a monte carlo fault study to specify how often this fault is likely to occur. |
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repair |
Hours to repair. |
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enabled |
{Yes|No or True|False} Indicates whether this element is enabled. |
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like |
Make like another object, e.g.: |