JNR developed the EF81 type electric locomotive in order to operate on the Nihonkai-Jyukan Line which is electrified by 1,500VDC, 20,000V 50HZ AC, and 20,000V 60HZ AC in 1968. The EF81 is specially designed to be compatible with this power supply. The EF81 requires heavy protection against cold weather and snow, because EF81 is operated where it snows heavily, and is equipped with special equipment to make the car body lighter.