The Siemens 5SV8703-0KK is a SENTRON summation current transformer designed for AC systems, rated at 200 A operational current with a 70 mm internal diameter. It's a type A device — meaning it detects both AC and pulsating DC residual currents, which is the standard for modern RCD compatibility in mixed-load panels. The 70 mm window passes bundled conductors up to that diameter, so it fits main feeders or multiple smaller circuits bundled through a single core.
Rated operational current of 200 A means this transformer sums the currents of up to 200 A per phase passing through its 70 mm window. The minimum detectable residual current is 30 mA — that's the trip threshold for standard 30 mA RCDs downstream, so it pairs directly with a 30 mA residual current device for personnel protection. Voltage rating tops out at 720 V AC at both 50 Hz and 60 Hz, covering 400 V and 690 V systems common in industrial distribution. Surge voltage resistance of 4 kV gives it basic impulse withstand for installation in standard LV switchgear. Wire length from the transformer to the evaluation unit is limited to 10 m — keep that in mind when routing in a large panel; exceeding it risks nuisance tripping or desensitization. The screw-type terminals accept 0.13 mm² to 2.1 mm² conductors, which covers standard control wiring up to about 14 AWG. Protection class at the terminals is IP20 — finger-safe but not washdown-rated, so mount inside an enclosure.
Deployment context
Mounts inside a distribution panel or switchgear cubicle — the 70 mm ID passes busbars or bundled cables, and the compact footprint (130 mm wide × 110 mm deep × 33 mm tall) fits standard DIN-rail or backplate layouts. The type A design means it's suitable for circuits with electronics, VFDs, or other loads that generate pulsating DC fault currents, not just pure AC sine-wave faults.