Description
Product Overview
The rotor earth fault protection relay 50N/51N is suitable for protecting generators with hydro turbine capacities not exceeding 10 MW and steam turbine generator capacities not exceeding 100 MW. Together with generator differential protection and generator backup protection, it forms a comprehensive generator protection system. It can be installed in a centralized panel or distributed across multiple locations.
Protection Configuration
- The generator rotor is grounded at one point
- Two-point grounding of the generator rotor
Measurement and Control Functions
- Analog signals: Ue, Rg, K
- Configure 21 channels of active AC/DC 220 V or DC 110 V digital input (specify when ordering)
- Equipped with 12 protection outputs; 1 signal output; 1 power failure output
Communication Mode
- Optional: RS-485, CAN bus, Ethernet, IEC 60870-5-103 (IEC-103)
Time synchronization function
- Supports communication-based time synchronization, SNTP, and message-based time synchronization; features a configurable dedicated B-code time synchronization interface (which can be switched to use the RS-485 port); supports IRIG-B time synchronization.
Printing function
- The device supports dot-matrix printers with serial communication and can print content such as setpoints and event logs.
Electrical Specifications
Power supply
- AC: 85 V to 264 V; 47 to 63 Hz; harmonic distortion not exceeding 15%
- DC: 100 V to 370 V, with a ripple coefficient of no more than 5%
Rated DC Parameters
- Excitation voltage: 10–500 V
Overload capacity
- AC current circuit: Continuous operation at up to 2 times the rated current; 10 times the rated current is permitted for 10 seconds; 40 times the rated current is permitted for 1 second
- AC voltage circuit: Continuous operation at 1.5 times the rated voltage
Device storage capacity
- Trip Reports: The device can store the most recent 128 trip reports in a cyclical manner.
- Operation Log: The device can cyclically log the most recent 128 device operation events.
- Device Self-Test: The device can cyclically record the most recent 32 sets of self-test data.
- Fault Recording: The device can cyclically record the most recent 32 fault recording events
Environmental Conditions
- Operating temperature range: -10°C to 55°C
- Operating temperature range: -40°C to 70°C
- Storage temperature: -40°C to 80°C
- Relative humidity: 5%–90% (no condensation inside the product)
- Altitude: ≤2000 m; for altitudes above 2000 m, adjustments shall be made using the altitude correction factor.
Schematic
Protection Setting Sheet
| No. | Setting Name | Setting Range | Unit | Default Value | Remark |
|---|---|---|---|---|---|
| 1 | One-point Ground Fault Setting | 0.1–100 | kΩ | 10 | Unit: kΩ (kiloohm) |
| 2 | One-point Ground Fault Time Delay | 0–100.00 | s | 5 | Adjustable on-site as required |
| 3 | One-point Ground Fault Mode | 0–2 | — | 2 | 0=Disabled, 1=Trip, 2=Alarm |
| 4 | Two-point Ground Fault Setting | 0.050–0.999 | % | 30% | 0.3, position deviation between one-point and two-point grounding |
| 5 | Two-point Ground Fault Time Delay | 0–100 | s | 2 | |
| 6 | Ground Protection Starting Voltage | 10–500 | V | 50 | Default: 50V; set according to actual excitation voltage |
Dimensions and Cutout Sizes
FAQ
Q:There are two principles underlying generator rotor grounding protection. What are they?
A:The principles of generator rotor grounding can be divided into two types: the ping-pong type and the injection type. These two methods must not be used interchangeably.
Q:How is relay protection for generator rotors typically used?
A:Generator rotor ground protection generally serves two functions: single-point ground protection and two-point ground protection. When a single-point ground occurs in the generator rotor, the protection device issues an alarm; when a two-point ground occurs, the protection device trips immediately.
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