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Test Interfaces for Power Systems

Interface Test System


ITS is a flush-mount test block for interfacing substation devices (protection relays, fault recorders, revenue meters, ... ) to the voltage and current transformers and to other equipment on the system side of a power grid.

STP is a test plug keyed to a particular configuration of ITS test blocks. Once inserted into the corresponding test block, the STP plug isolates the substation devices from the system side equipment while at the same time allowing connection of test equipment for secondary injection tests.

Key Features

  • 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 blocks have an extremely low internal resistance. This decreases the burden placed on instrument transformers and also reduces heat dissipation inside cabinets and 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 7 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.

Principle of Operation

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.


Cases for STP Test Plugs
Rugged case for STP Test Plugs and test probes.
Individual Test Probes
These test probes will fit all ITS Test Blocks, regardless of configuration. Keying in the probes prevents insertion into wrong circuits (ie, 2-pole current probes can only be inserted into a 2-pole current part of an ITS Test Block). Current probes include internal shorting bridge.
Current Measurement Probe
This special test probe allows the connection of current measurement device or a shunt. The AWG 13 (2.5 mm) connection cable has a length of 118.11 inch (3 meters). The test probe are available with c-hook terminals or banana plugs at the tip of the cable.
ITS 19´´ Rack Plates
SecuControl offers metal plates for installation of ITS test blocks in 19” racks that come painted in various colors and with various cutouts for ITS test blocks, in standard heights of 2U or 3U.

Please consult our manual on the download section of this site for ordering information.



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