What would occur if the field circuit of a loaded shunt moto

What would occur if the field circuit of a loaded shunt motor were suddenly opened?

Solution

when fied is open then field current will be zero and so
field flux also tends to zero,as speed is inversaly
proportional to flux, motor will rotate at (infinite)high
speed then winding will burn

if as always protection is use or drive used for motor then
it will trip and stops motor and protect it from burning