Protection and control cabinets for the control buildings of two 35/10 kV substations: UFLS, line protection and CT/VT terminal boxes
A relay protection set for two 35/10 kV substations: a UFLS cabinet, a microprocessor line protection cabinet and four outdoor IP54 CT/VT terminal boxes with heating. Six products, Odesa, 2026.
A set of secondary circuit and relay protection equipment for the control buildings of two 35/10 kV substations: an under-frequency load shedding (UFLS) cabinet, a line protection and control cabinet built on a microprocessor relay, and four outdoor CT/VT terminal boxes. Six products, each with its own factory passport. Manufactured and tested at our factory in Odesa; a 2026 order.
The task
Reconstruction of the secondary circuits of two 35/10 kV substations: protection cabinets for the control buildings and outdoor terminal boxes next to the current and voltage transformers. Requirements:
- microprocessor-based protection with test blocks for checks without dismantling the wiring;
- UFLS — emergency under-frequency load shedding;
- outdoor terminal boxes with heating — switching CT and VT secondary circuits outdoors all year round;
- cabinets for both substations built to a single documentation set, labelled per site.
The solution
Line protection and control cabinet: an RS83-BC3 microprocessor protection relay made in Ukraine, test blocks in current and operational circuits — protection testing without unwiring; auxiliary relays with test buttons; mode selectors (main/backup/gas protection), buttons and indicator lamps on the front panel.
UFLS cabinet: an RZM-A under-frequency load shedding device (Ukrainian manufacturer), voltage and auxiliary relays, UFLS/reclosing stage selectors on the front, and a glass door for status checks without opening.
CT and VT terminal boxes (two per substation): outdoor IP54 execution with thermostat-controlled anti-condensation heating, lighting and a service socket; the VT box carries a voltmeter with a 0–40 kV scale and a phase selector; terminal blocks for metering and protection circuits, bottom cable entries.
All apparatus is mounted on wiring ducts with every wire labelled; each product has its own factory passport and nameplate.
The series product card: relay protection and control cabinets. For designers: the typical solutions "UFLS" and "КСО protection schemes".
Figures (from factory passports)
Control building cabinets (UFLS and line protection)
| UFLS | Line protection | |
|---|---|---|
| Rated voltage | 220 V, 50 Hz | 220 V, 50 Hz |
| Rated current of main circuits | 5 A | 10 A |
| Apparatus | RZM-A UFLS device | RS83-BC3 microprocessor relay, test blocks |
| Degree of protection | IP31 | IP31 |
| Dimensions (H×W×D) | 2200×800×600 mm | 2200×800×600 mm |
| Weight | up to 300 kg | up to 300 kg |
Outdoor terminal boxes
| VT box | CT box | |
|---|---|---|
| Rated current | 25 A | 5 A |
| Degree of protection | IP54 | IP54 |
| Heating | — | 75 W with thermostat |
| Instruments | voltmeter up to 40 kV | metering and protection terminals |
| Dimensions (H×W×D) / weight | 1200×600×360 mm / up to 75 kg | 1200×600×360 mm / up to 75 kg |
| Operating temperature | −40…+40 °C | −45…+40 °C |
The set: 6 products for two 35/10 kV substations · manufactured in 2026, Odesa, Ukraine.
Photo report: control building cabinets and outdoor boxes
We will build to your protection scheme
Relay protection cabinets, UFLS, terminal boxes and secondary switching for substations — from the diagram to factory testing. Leave a request and our engineer will work through your specification.
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