Breaker (with arc)

Opens while control is true; an arc sustains current until it quenches.

  • Boolean
  • electrical
  • Modelica Standard Library
  • 3 ports
  • 5 parameters
BlockBreaker (with arc)KindbreakerLibrarySemiconductors

Description

An opening switch with a simple arc model. While control is false it is closed. When control turns true, an arc keeps current flowing with a voltage that starts at V0 and rises at dVdt up to Vmax.

The arc quenches once the current has fallen to the leakage level, and the switch then blocks with conductance Goff until it closes again.

Example

Switches and a breaker An ideal switch, closing and opening switches, a two-way switch, and a breaker that opens an inductive circuit.

10 V Ai ALoad AIdeal switchGate 5 HzGround A10 V Bi BClosing switchClose at 0.1 sLoad BGround B10 V Ci COpening switchOpen at 0.1 sLoad CGround CL 10 mH10 V Di DBreakerTrip at 0.1 sLoad DGround D10 V Ei ETwo-way switchChange over at 0.1 sLoad 10 ΩLoad 20 ΩGround E
In Gradara, select a Breaker (with arc) block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:DC voltageIdeal switchCurrent sensorGroundPulseResistorInductorSwitch (Boolean)Opening switchChangeover switchBoolean step

Ports

Inputs 1

  • tripcontrolBoolean

    Boolean trip command: true opens the contacts.

Conserving terminals 2

  • +pelectrical

    Terminal 1. Current into p is counted as positive.

  • −nelectrical

    Terminal 2.

Parameters

  • On resistanceRon0.00001 Ω

    ≥ 0

    Closed-contact resistance, in ohms. 0 or more.

  • Off conductanceGoff0.00001 S

    ≥ 0

    Conductance after the arc quenches, in siemens. 0 or more.

  • Arc voltageV030 V

    ≥ 0

    Arc voltage at the instant of opening, in volts. 0 or more.

  • Arc voltage slopedVdt10000 V/s

    ≥ 0

    Rate at which the arc voltage rises, in V/s. 0 or more.

  • Maximum arc voltageVmax60 V

    ≥ 0

    Maximum arc voltage, in volts. The arc voltage stops rising here; reaching it does not by itself quench the arc.

Equations

Modelica
v = p.v − n.v, i = p.i
Closed: v = Ron · i
Arcing: v = min(Vmax, V0 + dVdt · (time − tOpen)) · sign(i)
Quenched once |i| ≤ Goff · |v|; then i = Goff · v

Implementation

Modelica Standard Library 4.1.0Modelica.Electrical.Analog.Ideal.OpenerWithArc
MSL documentation

Assumptions and limitations

  • The arc voltage depends only on time since opening, not on current, cooling, or contact gap. There is no re-strike after quenching.
  • In an AC circuit the arc quenches at the next current zero. In a DC circuit it quenches only if the arc voltage can drive the current to zero, typically when Vmax exceeds the source voltage.

See also

Select a block in Gradara and press F1 to open its page offline.