DC Power Panels and Specialty Electrical Equipment

YF-GZDW supplies DC to the protection, control and operating circuits, at DC220/110/48/24 V; YFFZ is a load bank that load-tests a generating set or a source, at 3–12 kV on the high-voltage side and 400 V on the low-voltage side, 1–3000 kW; YF-BZD is the transformer neutral earthing resistor cubicle and sets how large the fault current is on a single phase-to-earth fault; VDY4-12 is a 12 kV embedded-pole vacuum circuit breaker, the make-and-break element of the main circuit. None of the four sits in the main distribution path, but a substation missing any one of them is incomplete.

From the DC load schedule and the emergency discharge time. First total the continuous and impulse loads of control, protection, signalling and DC emergency lighting, then choose the battery capacity against the emergency discharge time, then set the charging module output current. Output voltage comes in four steps of DC220, 110, 48 and 24 V and output current in eight steps of 10, 20, 30, 40, 50, 60, 100 and 200 A, with the battery either nickel-cadmium or lead-acid. Send the DC load schedule and the emergency discharge requirement and a configuration can be proposed.

Input voltage AC380 ±15 % at 50 ±5 %; voltage regulation and current regulation both not worse than ±0.5 %, ripple factor not above 0.1 % and whole-unit noise not above 55 dB; cooling is intelligent forced air and natural convection, and the duty is continuous.

From the fault current the system is intended to limit on a single phase-to-earth fault, working back to the resistance value and the current duration. The product applies at 3, 6, 10, 20 and 35 kV with a permissible current of 5–2000 A and durations of 10 s, 30 s, 60 s, 10 min and continuous, at a resistivity of 1.04–1.06 μΩ·m. The resistor cubicle is a standard product and can run in parallel with a resistor or a reactor, which suits a network whose earthing resistance has to fall as it grows.

A separate zigzag earthing transformer has to be installed and the earthing resistor cubicle pairs with it. The earthing transformer can be cast-resin or oil-immersed: with a cast-resin dry-type one the cubicle can be combined into one enclosure or split into two, outdoor cubicles usually combined and indoor ones usually split; with an oil-immersed one the earthing transformer stands outdoors while the resistor cubicle sits indoors or outdoors, connected by cable.

Rated power 1–3000 kW, rated voltage 3–12 kV on the high-voltage side and 400 V on the low-voltage side, rated frequency 50–60 Hz, load accuracy ±3 %, three-phase imbalance ±3 %, forced-air cooling, manual or automatic control, indoor or outdoor installation, in fixed or mobile construction. Several load units of the same test voltage class can be paralleled to reach the total test capacity required. The computer control software runs the specific test parameters for a generating set and produces curve test reports with print and print preview.

The operating mechanism and the breaker body are of integrated design, so it serves either as a fixed-mounted unit or, with the dedicated racking mechanism, as a withdrawable truck unit. Rated voltage 12 kV, rated frequency 50 Hz, 1 min power-frequency withstand 42 kV to earth and 48 kV between phases, lightning impulse withstand 75 kV to earth and 85 kV between phases at peak, rated short-circuit breaking current in four steps of 20, 25, 31.5 and 40 kA, rated short-circuit duration 4 s and mechanical life 10000 operations. The specific pairing of rated current with breaking current is confirmed against the project single-line diagram.

Yes. The DC power panel and protection panel line-up commonly ship with a secondary-equipment module, the earthing resistor cubicle goes with a primary-equipment module in either indoor or outdoor form, and the load bank is usually independent mobile equipment. The enclosure, panel arrangement, auxiliary systems and interface integration come from the prefabricated power module line, and the delivery boundary is settled once at contract stage.