A $4$-pole, separately excited, wave wound $DC$ machine with negligible armature resistance is rated for $230$ V and $5$ kW at a speed of $1200$ rpm. If the same armature coils are reconnected to form a lap winding, what is the rated voltage (in volts) and power (in kW) respectively at $1200$ rpm of the reconnected machine if the field circuit is left unchanged ?
1. $230$ and $5$
2. $115$ and $5$
3. $115$ and $2.5$
4. $230$ and $2.5$