SAX / PAX
DIN rail or surface mounted test interface
The SAX is a surface-mount test block that ensures secure and reliable interfacing between substation devices, such as protection relays, fault recorders, revenue meters, and a diverse range of components within the system side of the power grid. Notably, the SAX serves a dual purpose by functioning as both a terminal block and a test block. This allows for space and wire savings within the panel, as well as optimization in design.
The PAX is a meticulously designed test plug specifically tailored to match the precise configuration of the SAX test blocks. Upon insertion into the corresponding test block, the PAX adeptly isolates the substation devices from the system side equipment. This isolation serves the crucial purpose of safeguarding the substation devices while simultaneously facilitating seamless connectivity to test equipment. As a result, the PAX enables the execution of secondary injection tests with ease and precision.
- Reducing Panel Space and Wiring Time Needs – SAX combines the functions of two devices: a terminal block and a test block. This means that less panel space and less wiring is required. SAX can be placed in areas where normal test switches cannot be installed – easily mounted on a DIN rail or via screws.
- Finger-safe – The front of the SAX terminal / test block has no exposed metallic parts, greatly increasing safety during testing.
- Patented Keyed Test Plugs – Test plugs are keyed to the corresponding test block, preventing mistakes and errors during testing. Current circuits are keyed different than other types of circuits, allowing the use of individual test probes while maintaining the safety benefits.
- Built-in Time Sequencing – When a test plug is inserted into a SAX test block, contacts are opened in a pre-defined sequence. This is done to prevent false trips from activating the breaker, greatly simplifying the task of testing. The intelligence is built into the plug: different length fingers create the sequence and fixed current shorting bars provide safe and reliable make-before-break current shorting. When the PAX test plug is removed from the block, contacts are closed in the reverse order, with the trip contacts being the last to close.
- Less than 2 mΩ internal resistance
Thanks to the patented construction, SAX / PAX test interfaces have an extremely low internal resistance. This ensures a lighter load on instrumentation transformers and no impact on heat generation within panels.
- Many sizes and configurations
The right SAX for you either already exists or can easily be created. The 4600 series includes popular models with 7, 10, 14 and 20 poles. Custom configurations have 4 to 20 poles and can be built with any combination of currents, voltages or trip signals, as well as custom labeling.
- Compatible Test Plugs – STP and PAX Test Plugs and Probes.
Closed circuit
A SAX terminal / test block contains modular units (or “poles”) each allocated to a current, voltage, or signal / trip circuit. Each circuit is connected through the block via two silver-coated copper contacts, pressed securely together by two pressure springs to create a highly conductive electrical connection. In this situation, an electrical connection is established between the device side (B) and the system side (A).
Open Circuit
When testing, the corresponding PAX test plug or test probe is inserted into the SAX. In this position, the device and system sides of the terminal / test block are isolated from each other. The test plug includes internal shorting bridges for the current circuits. When the test plug is removed from the test block, the internal springs force the contacts back together, returning the circuits to their normally-closed position.
Signal Injection
Banana jacks in the test plug allow the connection of a test set to the device side of the terminal / test block and the associated signal injection. Access to the system side is also provided.
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