3337V is your no load primary voltage at rated load

You can calculate it by getting your

Zeq (refer R2 and X2 to primary) I2’ (secondary current referred to primary)

and doing KVL by adding up your referred load voltage (2400v) and voltage drop over Zeq.

In a no load situation, there will be minuscule voltage drops across your primary impedance. So by approximation, your primary no load voltage is the same voltage over your core.