demo, Sql Server - rextester

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--Sql Server 2014 Express Edition
--Batches are separated by 'go'

WITH yourTable AS (
    SELECT 201010 AS Meter_id, '2018-09-27 00:00:00' AS Realtimeclock, 1.0 AS I_Y, 2.0 AS I_B, 3.0 AS I_X UNION ALL
    SELECT 201010, '2018-09-27 00:30:00', 1.0, 2.0, 3.0 UNION ALL
    SELECT 201010, '2018-09-27 01:00:00', 1.0, 2.0, 3.0 UNION ALL
    SELECT 201010, '2018-09-27 01:30:00', 1.0, 2.0, 3.0 UNION ALL
    SELECT 201010, '2018-09-27 02:00:00', 1.0, 0, 3.0   UNION ALL
    SELECT 201010, '2018-09-27 02:30:00', 1.0, 0, 0     UNION ALL
    SELECT 201010, '2018-09-27 03:00:00', 1.0, 2.0, 3.0 UNION ALL
    SELECT 201010, '2018-09-27 03:30:00', 1.0, 2.0, 3.0
),
cte1 AS (
    SELECT t.*, ROW_NUMBER() OVER (PARTITION BY Meter_id ORDER BY Realtimeclock) rn
    FROM yourTable t
),
cte2 AS (
    SELECT t.*, ROW_NUMBER() OVER (PARTITION BY Meter_id ORDER BY Realtimeclock) rn
    FROM yourTable t
    WHERE I_B <> 0
),
cte3 AS (
    SELECT t1.*,
        t1.rn - t2.rn AS diff
    FROM cte1 t1
    INNER JOIN cte2 t2
        ON t1.Meter_id = t2.Meter_id AND t1.Realtimeclock = t2.Realtimeclock
)

SELECT
    Meter_id,
    MIN(Realtimeclock) AS start_time,
    MAX(Realtimeclock) AS end_time,
    COUNT(I_Y) AS I_Y,
    COUNT(I_B) AS I_B,
    COUNT(I_X) AS I_X
FROM cte3
GROUP BY
    Meter_id,
    diff;

View schema
Execution time: 0 sec, rows selected: 2, rows affected: 0, absolute service time: 0,19 sec