device: 7SL87 differential/distance protection, 1 /3-pole dual-end fault protection, expandable housing type: flush mounting; BI: 57; BO: 53 (29ST + 8F + 16HS + 0P); I: 4 (protection); U: 4 ( standard); measuring transducer inputs: 0 (20 m A or 10 V, fast), 0 (20 m A, normal); housing width: 1 x 19'' + 2/3 x 19''; modules in 19" row 1: IO 208, PS201, IO205, IO206, IO20 9, IO209; modules in 19" row 2: PS 203, IO209, IO209, CB202; LEDs/push-buttons: 16 LEDs; operation panel: integrated; key switch: without; display type: small display;