**Sheng Xu Provides: The Basic Principles of Microcomputer Relay Protection Calibrator**
**1. What is the Function of Relay Protection and Safety Automatic Devices?**
Relay protection and safety automatic devices play a crucial role in maintaining the stability and reliability of power systems. When a fault occurs in any component of the system or when the system itself is at risk, these devices are responsible for sending timely alarm signals to operators or directly issuing trip commands to circuit breakers. This helps prevent further damage, minimize downtime, and ensure the safe and continuous operation of the power grid.
**2. What is the Task of Relay Protection in the Power System?**
The primary tasks of relay protection include:
(1) Detecting faults in protected components and quickly issuing a trip command to the nearest circuit breaker, isolating the faulty section from the rest of the system. This helps reduce damage to equipment and maintain stable power supply.
(2) Monitoring abnormal operating conditions of electrical equipment and sending alarms or initiating automatic adjustments. These actions allow operators to respond promptly or enable the system to self-correct. Some protection functions may include time delays to avoid unnecessary tripping during transient disturbances.
**3. Commonly Used Types of Relay Protection**
There are several types of relay protection used in power systems, including:
- **Current Protection:** Based on current increase during a fault, typically implemented with two or three stages.
- *Instantaneous Current Trip:* Reacts to severe faults and trips quickly.
- *Time-Delayed Instantaneous Trip:* Used on 35kV lines to avoid tripping due to low-voltage side faults.
- *Time-Overcurrent Protection:* Designed for faults at the end of a line or through high-resistance short circuits.
- **High-Frequency Protection:** Involves injecting high-frequency signals into transmission lines to detect internal faults. If a fault is detected within the protected zone, both ends of the line will trip simultaneously. This method does not interfere with normal power transmission and requires daily channel testing.
- *Blocking Type:* High-frequency blocking signals are continuously sent from both ends. During a fault, the signal stops, allowing the relays to trip.
- *Permissive Type:* Normally no signal is sent. Upon detecting a fault, an enabling signal is transmitted, and the circuit breaks after receiving the signal from the other side.
**4. Basic Requirements for Relay Protection in the Power System**
The key performance requirements for relay protection are:
- **Reliability:** Must operate correctly under all conditions.
- **Speed:** Must act quickly to limit damage.
- **Selectivity:** Must isolate only the affected part of the system.
- **Sensitivity:** Must detect even small faults effectively.
**Technical Parameters of the Microcomputer Relay Protection Calibrator**
1. **Current Source (BY660):**
- AC: 0–40A per phase, 0–120A three-phase parallel
- DC: 0–30A per phase, 0–90A three-phase parallel
- Power: 400VA per phase
- Accuracy: ≤0.2%
- Response Time: <160μs
- Resolution: 1mA (AC), 2mA (DC)
2. **Voltage Source:**
- AC: 0–125V per phase
- DC: 0–220V per phase
- Auxiliary Power: 0–125V AC or 0–220V DC
- Power ≥130W
- Accuracy: ≤0.2%
- Response Time: <120μs
- Resolution: 2.5mV (AC), 3.5mV (DC)
3. **Frequency:** 0–1000Hz, resolution 0.001Hz (for frequency), 0.1Hz (at 1kHz)
4. **Phase:** 0–360°, resolution 0.1°, accuracy 0.1°
5. **Time Range:** 0–9999.999s, ±1.0ms
6. **Switch Input:** 7 pairs of dry contacts, 10–250V DC with potential contact
7. **Switch Output:** 3 pairs of dry contacts (250VAC, 2A)
8. **Power Supply:** 120–250V AC, 50/60Hz
9. **Dimensions:** 450mm × 150mm × 370mm
10. **Weight:** 11kg
**Main Features of the Microcomputer Relay Protection Calibrator**
1. **Intelligent Host:** Uses a DSP chip for control and 16-bit DAC output, generating 2000 points per cycle for high-quality sine waves.
2. **Stand-Alone Operation:** Operated via a large LCD display using a mouse, supporting full Chinese interface for testing various relays and simulating complex faults.
3. **Computer Connection:** Compatible with Windows XP software for automated testing, data storage, vector diagrams, and report generation.
4. **Graphic Display:** 320×240 dot matrix screen with clear and intuitive Chinese interface.
5. **User-Friendly Design:** Equipped with a photoelectric rotary mouse for easy operation without requiring computer skills.
6. **Compact Design:** Uses switching power supply and amplifier technology, weighing only 11kg.
7. **Modular Construction:** All plug-ins are independent, allowing for easy upgrades and maintenance.
8. **Flexible Configuration:** Supports 6-phase current, 5-phase voltage + 2-phase current setups.
9. **Calibration Software:** Allows users to verify the accuracy of the device.
10. **GPS Integration:** Enables synchronized testing at both ends of a transmission line.
11. **Comtrade Playback:** Can replay fault records in Comtrade format.
12. **Power Factor Correction:** Achieves efficiency of 95% or higher.
13. **Voltage Tolerance:** Operates normally even when input voltage drops to 120V.
14. **Hardware Protection:** Ensures long-term reliability and safe operation.
This comprehensive calibrator is ideal for engineers and technicians involved in the testing and maintenance of relay protection systems, offering precision, flexibility, and ease of use.
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Ningbo Safewell Plumbing Co., Ltd. , https://www.safewellbrass.com