This part of IEC 60834 applies to teleprotection command systems used to convey command information, generally in conjunction with protection equipment. It aims at establishing performance requirements and recommended testing methods for command type teleprotection equipment. The information conveyed by the teleprotection equipment can be in analogue or digital form. The command type teleprotection equipment referred to in this standard can be power line carrier equipment or voice frequency equipment which is used in connection with various telecommunication systems, such as power line carrier (PLC), radio links, optical fibre, rented circuits, leased or privately owned cables. In addition the command type teleprotection can be digital equipment which is used with a digital telecommunication system or media such as optical fibres, radio links, leased or privately owned digital links. The command type teleprotection equipment may be separate or provided as an integral part of the protection equipment. In addition to teleprotection equipment performance tests, tests have to be carried out on the power supply of the teleprotection equipment. All the tests should be regarded as type tests. NOTE – According to the International Electrotechnical Vocabulary (IEV), a type test is defined as a test of one or more devices made to a certain design to show that the design meets certain specifications.