Electronic Products & Technology

Push-in terminal blocks and modular machine design

By Phoenix Contact   


Modular machine design is on the rise. Users are demanding more from products along the entire process chain right up to the last component. Mechanical engineers base their strategic design decisions on their customers’ production requirements. This trend is known as ‘Lean Product Design’. The market is moving away from fully automated, complete production systems toward smaller production cells having standardized functional modules. Component manufacturers are also falling in line with this trend. The impact on terminal blocks is a need for time saving, for more flexibility and ultimately for an efficient system.

Short wiring time

This is not to say that lean product design means poorer quality or reduced availability. It simply describes a way to standardize predefined functional modules to meet customer demands. The production designs stipulate that the systems should be lean, cost-effective, and individually configurable.

Although the tried-and-tested screw connection technology still dominates the global market, spring connection technologies have also started gaining ground. Terminal blocks with push-in technology use compression springs to press the conductor against the live copper rail, thus forming an electrical connection (*See Figure 1).

Installers find this technology particularly useful. No tools are required for wiring, since the wire with ferrule is connected to the contact point directly. Although rigid or single-wire conductors are standard in building engineering, this is not the case in mechanical engineering. Previously, only thick, rigid conductors did the job, but now thin sensor cables are also used. Phoenix Contact’s terminal blocks with push-in technology (PT) are in line with these requirements. The innovative connection technology is much easier to use, reducing the required insertion force by 50%. Conductors with cross sections beginning at 26AWG can thus be wired without the need for tools.


Wiring without tools is also particularly useful in cramped, hard-to-access areas. Electricians at the end of the process chain can even work with one hand: forming a connection is as easy as grasping the conductor and plugging it in. Wiring work is thus made simpler and more ergonomic, leading to reduced wiring time and fatigue (*See Figure 2).

The wide variety of manufacturer-specific connection technologies used in all kinds of terminals, relays, and control units makes installers’ daily work more difficult. There is no standard way to position conductors and working tools in the components. Faulty wiring is often the result, which in turn may lead to system failures and even pose safety hazards. Phoenix Contact push-in terminal blocks have distinctive color-coded pushbuttons for clear identification. Operation and conductor insertion are optically and physically separated, thus ruling out any possibility of positioning the conductor incorrectly (*See Figure 3).

Safety factor

Full insulation also increases operational safety. Working on live systems contravenes both norms and accident prevention regulations, but it still occurs in real life. It is not uncommon to perform measurement and test procedures or to rewire during live operation. The Push-In technology actuation button provides secure contact protection with insulation to separate the internal contact elements reliably. It is thus not possible to come in contact with live parts.

Space saving

The signal and control wiring in the lower power range plays a key role in the system wiring. Machine functions are becoming ever more complex and there is less space for the increasing signal density. At Phoenix Contact, terminal block family with a 3.5mm pitch and Push-In technology has been developed specifically for these applications. These terminal blocks are particularly suited for control circuits, sensors, and actuators. In practice, wiring in the lower power range typically uses conductors with cross sections between 16 and 24AWG (figure 4).

Compliance with machine standards

The stringent safety regulations for connectors in compliance with the machine regulations per IEC 60204-1 have been followed. When connecting, contact is first made with the protective conductor. Connectors and basic terminal blocks are protected against finger contact in compliance with BGV A2.


Push-In terminal blocks are the newest generation in terminal block technology. They set a new standard for Terminal Blocks technology. These easy-to-use terminal blocks ensure short wiring times for all types of cables, reduce risk of faulty wiring, enabling tool-free wiring of the smallest cables without fatigue. Ultimately, Push-in technology makes system more flexible and economical in line with requirements for modular machine designs.


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