SSD K1H increases the short-circuit withstand of the surge-protection system from 25 kA to 100 kA while carrying an impulse current of 25 kA per path. The SPD backup device fits within four TH35 DIN-rail modules, replacing a panel-mounted switch-disconnector with NH knife-blade fuse-links - the manufacturer states switchboard space savings of up to 50%. Selection is reduced to a single item: one disconnector serves the entire K1H SPD series, eliminating the risk of installing a fuse-link with a current rating outside the range specified in the SPD datasheet. The fuse striker and microswitch transmit the backup-device state to the monitoring system, so supervision can detect both varistor end-of-life in the SPD and operation of the backup protection.
The disconnector carries lightning impulse current Iimp 25 kA with a 10/350 µs waveform and nominal discharge current In 25 kA with an 8/20 µs waveform. Short-circuit withstand Isccr is 100 kA, minimum trip current Itrip 1100 A, rated operating voltage Ue 500 V AC (50/60 Hz). It works with SPDs having maximum continuous operating voltages Uc of 175, 275, 320 and 440 V, in TT, TN and IT systems, for L–N, L–PE(N) and N–PE protection modes. Limited current per pole reaches 27.09 kA and Joule integral I²t per pole 363.5 kA²s. The Surge-Trap® K1H LF SPD itself has short-circuit withstand Isccr 25 kA and accepts a backup fuse up to 250 A gG.
The fuse-link is cylindrical, size 22×58 mm. Versions: SSD1H-2PG-M (45001202) in 1+1 configuration, SSD1H-3P-M (45001302) in 3+0, and SSD1H-4PG-M (45001402) in 3+1, occupying two, three and four modules respectively. The four-pole version is 140 mm wide, 126.5 mm high (127.5 mm with clip), 70 mm deep and weighs 0.93 kg. Temperature range −40…+80 °C, humidity 5–95%, operation up to 2000 m above sea level, IP20 protection, overvoltage category III, pollution degree 2, PA6 CT1 and PA66 CT1 enclosure with UL94 V-0 flammability class. Terminals accept 1.5–50 mm² solid and 1.5–35 mm² stranded conductors, tightening torque 4 N·m; signalling contact 240 V / 2.5 A AC or 24 V / 3 A DC.
A station main switchboard, auxiliary switchboard or vehicle charging supply circuit operates at 230/400 V with prospective short-circuit current increasing with the power rating of the supply transformer. Iimp 25 kA per path qualifies the combination for zones exposed to direct lightning current entering the building lightning-protection system. The manufacturer specifies the Surge-Trap® K1H 25 kA LF with SSD K1H combination for transformer stations. The product standard in the datasheet is given as draft technical specification prIEC TS 61643-06.
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