New, smaller installation requirements.
Edge-to-edge, the "D" (Din Rail) family provides more amps per square inch. POWER-IO was the leader in the development of an integrated solid state relay and heat sink as a single, thermally efficient unit. This product line was expanded to include models for 25 amps and 40 amps. POWER-IO now continues this leadership with the new Maximum Surge Survival technology that adds the triple layer of surge shielding to this family. Installation-friendly: less than 1.25 inches wide (25 amp unit) or 2.4 inches wide (40 amp unit), with finger-safe caged terminals and a universal mounting bracket for Din Rail mounting or bolt-on mounting. The new "D" design requires only 0.18 inches between relays for cooling -- an industry improvement that reduces your panel requirements by 30-60% compared to other din-rail, solid state relay products.
In addition, the new D family uses the latest international specifications including the A1, A2, L1, T1 terminal markings; a green LED for control input status; the latest CE specification EN 60947-4; and NO need for external filters in order to meet the CE noise specifications.
The complete part number might look like: DDA - 6V25 that stands for:
The new "D" family uses a performance-engineered heat sink and thermal transfer technology. Due to this, the D family can be installed on a din-rail with only 0.18 inches between relays for cooling purposes! Edge-to-edge, the D family provides more amps per square inch than other brands of industrially hardened, solid state relays. This means that it stands up better to installations where the ambient temperature is warm. Please note -- all D units are rated to operate in an environment of 40°C (104°F) without any derating compared to other units that may be rated only at 20 or 25°C and need to be de-rated at 40°C. The new CE standard EN60947-4 requires that all new solid state relays must meet their specifications at 40°C. The D family uses a highly efficient design so it generates less than 1 watt (25 amp units) or less than 1.2 watts (40 amp unit) per amp switched. This compares to other units that might generate 50-75% more heat per amp switched. The D family works harder -- runs cooler.