ABB CA-16 Manuals

ABB Automation Inc. Substation Automation and Protection Division Coral Springs, FL 33065 Instruction Leaflet All possible contingencies which may arise during installation, operation or maintenance, and all details and variations of this equipment do not purport to be covered by these instructions. If further information is desired by purchaser regarding this particular installation, operation or maintenance of this equipment, the local ABB Power T&D Company Inc. representative should be contacted. ! CAUTION Before putting protective relays into service, remove all blocking inserted for the purpose of securing the parts during shipment. Make sure that all moving parts operate freely. Inspect the contacts to see that they are clean and close properly, and operate the relay to check the settings and electrical connections. 1. APPLICATION The current transformers should not saturate when carrying the maximum external fault current. This requirement is met if the burden impedance does not exceed: where Np = proportion of total ct turns in use. VcL = Current transformer accuracy class C voltage. Iext. = maximum external fault current in secondary RMS amperes. (let Iext. = 100 if max. external fault current is less than 100A) Rs = current transformer secondary wind- ing resistance, ohms. For example, if the 400:5 tap of 800:5 C400 current transformers are used, Np = 400/800 = 0.50, if Iext. = 120A, Rs = 1.0 ohm the burden should not exceed: NpVpL Iext. 100 – ( )Rs – 1.33 Iext. ( ) ------------------------------------------------------------ for CA-16 applications NpVcL Iext. – 100 ( )Rs – Iext. -------------------------------------------------------------- for CA-26 appliations NpVcL Iext. – 100 ( )Rs – 1.33 Iext. ( ) -------------------------------------------------------------- = 0.05 400 120 – 100 ( ) – × × 1.0 1.33 × 120 ------------------------------------------------------------------------------- 1.13 ohms = Types CA-16 and CA-26 Percentage Differential Relays for Bus and Transformer Protection Effective: September 1995 Supersedes I.L. 41-337.3K, Dated October 1985 ( | ) Denotes Changes since previous issue 41-337.3L CONTENTS This instruction leaflet applies to the following types of relays: CA-16 Bus Differential Relay CA-26 Transformer Differential Relay The CA-16 relay should not be utilized for trans- former differential applications since it is too sensi- tive for overriding the inrush. Likewise the CA-26 relay should not be used for bus protection with the “four-circuit bus” connections of Figure 8. The CA-26 relay is suitable for combination bus-trans- former applications. See “CONNECTIONS”.