Interface Test System (ITS)
VDE Standard
The ITS is a flush-mount test block engineered to establish safe interfacing between substation devices, such as protection relays, fault recorders, revenue meters, and various components within the power grid’s system side, including voltage and current transformers.
Complementing the ITS test blocks, the STP is a purpose-designed test plug precisely matched to the specific configuration of ITS test blocks. Upon insertion into the corresponding test block, the STP plug effectively isolates the substation devices from the system side equipment. Simultaneously, it facilitates the connection of test equipment, enabling the execution of secondary injection tests with precision and accuracy.
- Finger safe – The front of the ITS test block and the matching STP test plug 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 STP test plug is inserted into an ITS 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 STP test plug is removed from the block, contacts are closed in the reverse order, with the trips contacts being the last to close.
- Less than 2 mΩ internal resistance – Thanks to the patented construction, ITS / STP 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 ITS test block 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.
- Standardized Testing Procedures – Choose a few different ITS/STP configurations that cover all of your testing needs and use standard test routines for similar devices. This will save time, increase operator safety, and avoid costly errors.
- Compatible Test Plugs – STP and PAX Test Plugs and Probes.
Closed circuit
An ITS test block contains between 7 and 20 modular units (or poles) each allocated to a current, voltage, signal or trip circuit. Each circuit is connected through the block via two silver-plated 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 STP test plug is inserted into the test block. In this position, the device and system sides of the 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 test block and the associated signal injection. Access to the system side is also provided.
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