Innovative Engineering: new series of Solar Relays

Zettler is responding to increasing demands for wider contact gaps in solar relays to fulfill ever higher isolation requirements in compliance with pertinent safety standards such as IEC 62109 and UL 62109. Equally important, as the demand for higher kVA capacities of solar inverters keeps expanding, higher switching currents need to be accommodated by relays used in applications.

PCB solar relay AZSR1200 (200 A)

Among the new developments is the 200 A extreme high power PCB solar relay AZSR1200 with an integrated patent-pending contact system. The conventional contact spring of the relay is replaced by several highly flexible copper strands requiring little to no initial spring tension. Only negligible amounts of friction and the elasticity forces of the copper strands have to be overcome to move the 200 A contact into its operating position. Another significant advantage is the avoidance of contact welding risks often associated with short circuit currents in conventional contact spring solutions. With the AZSR1200 contact system the stronger the surge current, the more the contacts are pressed together. Even temporary short-circuit currents of up to 3,000 A, do not pose any welding risks for the relay contacts.

• Designed for 50 kVA (single phase) / 138 kVA (three phase) solar systems
• Wide contact gap > 4.6 mm for up to 5,000 m above sea level
• Holding power < 0.6 W
• Dielectric strength 5,000 Vrms
• Isolation spacing greater than 8 mm
• UL, CUR and VDE anticipated

Solar Relay AZSR180 (80 A)

Equally innovative the single pole AC side 80 A solar relay AZSR180 features a thermally conductive copper bridge, riveted directly behind the contact studs of two movable parallel contacts. This patent pending “thermal bridge” allows the two parallel contact springs to be “thermally connected”. Therefore it provides for an even-leveled distribution of any excessive heat between the two contacts that can result from significantly uneven distributions of currents carried in one vs. the other contact. Even in the extreme instance of a total failure of one of the two parallel-connected contacts the “thermal bridge” of the AZSR180 prevents a critical overheating of the latter contact and thus the destruction of the relay.

• Designed for PV applications up to 20 kVA (single phase) / 55 kVA (three phase)
• Wide contact gap > 2.05 mm for up to 4,000 m above sea level
• Very low holding power < 100 mW
• Dielectric strength 5,000 Vrms
• Isolation spacing greater than 10 mm
• Reinforced insulation, EN 60730-1 (VDE 0631, part1), EN 60335-1 (VDE 0700, part1)
• UL, CUR and VDE anticipated

 AC side relay AZSR1120 (120 A)

Both design elements – the integrated contact system as well as the “thermal bridge” – have been combined in Zettler’s most recent development: the single pole 120 A AC side relay AZSR1120. The new relay requires only about 40 % of the volume space of the 200 A solar relay, yet still performs with very favorable, low self-heating characteristics.

• Designed for PV applications up to 30 kVA (single phase) / 83 kVA (three phase)
• Wide contact gap > 2.3 mm for up to 5,000 m above sea level
• Holding power < 300 mW
• Dielectric strength 5,000 Vrms
• Isolation spacing greater than 8 mm
• UL, CUR and VDE anticipated

Zettler has continually expanded its line of AC side Solar relays. It spans across an extended range of product characteristics covering PV inverter applications from under 20 kVA to over 100 kVA, handling continuous currents from 10 A to as high as 200 A, max. switching currents ranging from 12 A to 100 A, and featuring min. contact gaps from 1.5 mm to 4.6 mm. For a complete listing of Zettler’s relay solutions please visit the website. For technical information and preliminary datasheets please contact ZETTLER electronics GmbH.