When traveling outside the USA, there are some important considerations when using an oxygen concentrator. The most important factor is the electrical supply, which differs widely in both quality and quantity; though there are some possible other considerations to consider.
In the United States electrical current is standardized around 120 Volts AC (VAC), at 50 Hertz in either the NEMA 1-15 (Ungrounded) or NEMA 5-15 (Grounded) formats. This standard is used in several other countries as well. However, confusion and problems can arise from the exact same plug format being used in other countries with vastly different power standards.