Updating of UNIT-AP devices
Despite the difficulties of the current 2020, Unitel Engineering continues to work not only on the development of new devices, but also on the improvement of proven products. A new version of the UNIT-AP (Arc Fault Protection Device) was released In August.
Firstly, a version with support for point-type fiber-optic sensors (FOS) appeared in the line of devices (standardly manufactured in lengths of 3, 5 and 10 m).
A point FOS consists of a light-sensitive lens, a "point", which is connected to the UNIT-AP device by means of an optical fiber in an opaque shell. The use of point FOS can be recommended when access to the inside of the protected compartment is difficult, requiring a large amount of locksmith work (for example, the compartment is closed by welding or bolted joints). In this case, the optical guide can be mounted on the outer side of the compartment, and the sensitive part, "point" - through the compartment wall through a previously made hole.
The second significant change was the revision of the internal software of UNIT-AP devices, which makes it possible to generate three independent TRIP commands.
The previously functional control schemesupported two directions of shutdown and made it possible to carry out selective Arc Protection schemes only when a UNIT-AP device was installed in each cell.
The use of three directions of tripping in some cases allows selective protection against arc faults at a lower cost.
Pic.1 In this example (Pic.1), one UNIT-AP device protects two cells of the outgoing line: - when the cable entry compartment is closed, the switch of the corresponding OL is disconnected by means of solid-state relays with the shortest possible time; - when an arc fault is detected in the busbar compartments or the circuit breaker, the section power supply disconnection is applied to the common busbar.
Pic.2 Also, the use of three directions of shutdown allows you to implement more complex remote sensing schemes. For example, to build protection of a bushing for a section equipped with a voltage transformer (Pic.2): - in case of a short circuit on the buses, the switches of the main and backup power inputs to the section are turned off; - short circuit in the circuit breaker compartment is elimin