Sadly almost all aftermarket power cord manufacturers make power cords with a 20 amp IEC female connector with a NEMA 125V 5-15P 15 amp plug on the other end. And what's worst the power cord might even be UL listed.
The company that makes the power conditioner makes such a power cord.
Link
Silver Circle 5.0SE power conditioner
Not sure what good a 5Kva isolation transformer connected to a 120V 20 amp branch circuit let alone a 120V 15 amp branch circuit.
A 5Kva, 5000Va, transformer is good for 41.67 amps continuous FLA at 120Vac.
Available Power in = available power out - core loses.
In other words continuous available power for a 20 amp dedicated 120V branch circuit is 120V X 20 amps = 2400Va.
For a 120V 15 amp dedicated branch the continuous available power is 120V X 15 amps = 1800Va.
If the unit will be plugged into a 120V 15 amp convenience outlet branch circuit that is sharing other loads there is the possibility when the unit is first powered on it may trip the 15 amp branch circuit breaker at the electrical panel due to inrush current.
.
The company that makes the power conditioner makes such a power cord.
Link
Silver Circle 5.0SE power conditioner
Not sure what good a 5Kva isolation transformer connected to a 120V 20 amp branch circuit let alone a 120V 15 amp branch circuit.
A 5Kva, 5000Va, transformer is good for 41.67 amps continuous FLA at 120Vac.
Available Power in = available power out - core loses.
In other words continuous available power for a 20 amp dedicated 120V branch circuit is 120V X 20 amps = 2400Va.
For a 120V 15 amp dedicated branch the continuous available power is 120V X 15 amps = 1800Va.
If the unit will be plugged into a 120V 15 amp convenience outlet branch circuit that is sharing other loads there is the possibility when the unit is first powered on it may trip the 15 amp branch circuit breaker at the electrical panel due to inrush current.
.