Will a 115V 60Hz work in a 120V 60Hz power supply?

Answer 1

You don't mention what device, but the answer is probably NO. 50hz and 60hz signals will act differently in reactive components such as Transformers, coils, capacitors, etc.

Paulev is correct that it would act differently on inductive/reactive devices, especially transformers. The device to be discussed here is the transformer as it is most present in all electronic equipment. Based on theories, a 50Hz transformer will perfectly work on a 60Hz Power system but not vice versa. Assuming the transformer's specs are, P=1kVA, L=1H, R~0 ohm. At 50Hz the impedance will be Z=sqrt(Inductive Reactance=2 x Pi x 50 x L), thus the ampacity (Ip=sqrt(P/Z)) of the magnetic wire at the primary is 1.79A.

Using the same steps at 60Hz. The current drawn by the the transformer will be 1.63A which is within the ampacity of the magnetic wire. therefore a 50Hz appliance can be used on a 60Hz supply without any problem.

Answer 2

For safety reasons, this is not recommended. Many 60 Hz electronic devices can overheat causing the risk of fire by running them on 50 Hz power sources. Additionally, the output of the device can be affected by lower than rated Hz input. This could cause damage to other devices that are attached to it (e.g. battery chargers). Always refer to the operators manual for the primary voltage/Hz requirements. Contact the manufacturer if you wish to operate the device outside of their published requirements.

Answer 3

Yes, 115V 60Hz will work in a 120V 60Hz power supply.