A little untypically for multi-connectors the series AK(Z)4551 and AK(Z)4951 are not only square, but in fact spiced up by a design agency.
Until the presentation of the series 4551 on the electronica in autumn 2010 the outer appearance of a terminal block of the whole terminal blocks industry followed strictly the function. Therefore “form follows function” generated functionally, but emotionless products. The target of the series 4551 and 4951 was to combine attractive design with additional benefits of functions. In close collaboration of the design agency and PTR’s development department two series were formed not only being an eye-catcher, but also having that certain something:
The push buttons are enlarged, so they can include the printing area which is normally positioned above the push buttons. Hereby the printings’ contrast and therefore the readability also under bad lighting conditions is increased. The edged recessed grips make it easier to pull the terminal block off the pin strip, the test jacks are positioned above the push buttons, hence easy to be reached. AK4551 in spacing 3.5 mm resp. AKZ4551 in spacing 3.81 mm hold stranded wires with or without ferrules up to wire size 1.5 mm² and solid wires up to 2.5 mm² safely. Beyond that the AK4951 and AKZ4951 in spacing 5.0 mm resp. 5.08 mm can also clamp stranded wires up to 2.5 mm² wire size. Having certifications from UL and VDE with 10 A rated current (series 4551) and UL 10 A and VDE 12 A (series 4951) both design series can be used in manifold applications. But hiding of multi-connectors is necessary nevermore.