crowbar circuit OrCAD simulation

[Skyland]

I have a couple of issues with the simulation;

1. : the zener diode has Vz at 4.7V, it is not behaving as expected since it is reducing the supply voltage by 4.7 instead of setting it to that voltage.
2. : the SCR is not triggering and short circuiting the PSU.
3. : Is there a way to add a spice model to a thermal fuse in capture.
4. : Any recommendations on the values of the resistors and capacitor used?

[JacobPilsen]

It looks You don't have catode of SCR connected to GND line.
(I don't see the node there.) That line is not straight. Shame OrCad.

In this simulation, there is a probability, that nominal current of Zener is lower that nominal Ig of this SCR. So SCR doesn't have enough triggering current (in simulation).

[PedroDaGr8]

It looks You don't have catode of SCR connected to GND line.
(I don't see the node there.) That line is not straight. Shame OrCad.

In this simulation, there is a probability, that nominal current of Zener is lower that nominal Ig of this SCR. So SCR doesn't have enough triggering current (in simulation).

He's right, look at the cathode line of the SCR there is no pink ball denoting a connection there.