General information
On-load tap-changer devices of the RNTA type for a rated voltage of 35-110 kV, rated currents of 630, 800, 1250 A are designed for built-in step regulation under load of voltage of three-phase general purpose power transformers with regulation.
RNTA devices are manufactured in various designs depending on the rated current, rated voltage, number of stages, and control circuit.
RNTA devices are designed to operate in transformer oil at oil temperatures from 100°C to minus 25°C, as well as up to minus 60°C without switching.
Climatic modifications U1, HL1 and T1.
Design
On-load tap-changer devices type RNTA of submersible design are built into the transformer tank. On-load tap-changer devices consist of main components: contactor, selector and drive. Devices, as a rule, operate in automatic mode from an automatic control unit. The following are supplied complete with on-load tap-changers:
- automatic control unit (voltage regulator), which provides a command to turn on the on-load tap-changer. The voltage regulator operates automatically when the voltage at the transformer terminals changes;
- a protective relay that issues a signal to turn off the transformer if the PU contactor is not operating correctly;
- temperature sensor-relay that interrupts the on-load tap-changer control circuit when the oil temperature is below minus 25°C.
The devices allow remote control and manual control from the handle when setting up or testing the transformer.
Main parameters and technical characteristics of on-load tap-changer devices type RNTA
| Parameter name | Magnitude | |||
| Rated voltage, kV | 35, 110 | |||
| Rated current, A | 630 | 630 | 800 | 1250 |
| Stage voltage, kV | 3.0 | 2.4 | 2.5 | 2.0 |
| Number of control stages | ||||
| Short circuit test current, steady-state rms value, kA | 8.0 | 8.0 | 10.0 | 12.5 |
| Mechanical wear resistance resource, not less than thousand switchings | 500 | 1000 | 500 | 500 |
| Drive PDP-6U, PDP-6UA | ||||
| Switching time from one fixed position to another, s | 5.7 | |||
General view and overall dimensions of on-load tap-changer devices type RNTA-Y-35... 110/630... 1250
General view and overall dimensions of the on-load tap-changer type RNTA-III-35/1250
