ABB has continued its string of assessments for feeder terminals used in the protection, control and measurement of medium-voltage (MV) networks by gaining acceptance for its new REX521 feed protection relay which is ideally suited for G59/1 embedded generator applications. This type assessment, managed by the Energy Networks Association (ENA), is an important step in obtaining product acceptance by National Grid and other leading customers in the UK electricity supply industry.
The REX521 uses the same protection functions as ABB’s REF541/3/5 feeder terminals that have already gained ENA acceptance, but is housed in a more compact, cost-effective design. It is primarily intended for use in distribution substations to provide short-circuit, over-current and earth-fault protection, as well as auto-reclosing of substation feeders.
In its H50 version, the REX521 is suitable for installation where embedded generators connect to a public supply network. While voltage and frequency protection are normally used to disconnect generators in the event of a loss of mains condition, the REX521