Environmental conditions
1. Ambient temperature and humidity
• Ambient temperature:
Computer room (with air conditioning): Summer 23±2℃ ; Winter 20±2℃ , hourly temperature change rate <5℃/ hour
On-site conditions: 0~40℃ , temperature change rate <5℃/ hour
• Relative humidity: Computer room (with air conditioning): 45%-65% On-site: 20%~90% (non-condensing)
2. Dust
Dust prevention measures should be considered based on different installation sites, using enclosed cabinets and ventilation holes with filters.
Computer room (with air conditioning): Dust particle size > 0.5μm, number < 3500 particles / liter
On-site: Dust particle size > 0.5μm, number < 18,000 particles / liter
3. Altitude
No more than 2000 meters.
4. Vibration and shock
The monitoring system equipment operates for a long time under the conditions of vibration frequency of 2~100Hz , peak -to- peak amplitude of less than 0.5mm , and acceleration not exceeding 0.5 times the acceleration due to gravity.
5. Noise Limitation
In the main computer room and central control room, the noise generated by the equipment of this system is less than 60 decibels.
6. Install wiring
The installation locations of wiring, cables, wires, and junction boxes or patch panels are convenient for users to connect wires. Each patch panel (box) has a certain number of spare terminals. The terminal connections inside the patch panel (box) are reliable and prevent loosening during vibration. The terminal blocks are equipped with protective covers. Wiring is neatly arranged, securely bundled, and firmly fixed. All wiring is marked, and the markings conform to national standards.
7. Electromagnetic interference and electromagnetic compatibility
Electromagnetic interference limit: No more than 1 volt / meter ( 30~50MHz electromagnetic waves) at a distance of 1 meter from the equipment.
Electromagnetic compatibility: The equipment in this system shall operate normally in the radiation environment specified below. If the radiation in the installation environment exceeds the allowable electromagnetic compatibility limit of the equipment, the installation environment shall be improved to meet the electromagnetic compatibility requirements.
• Radio Interference ( RI ): 30~500MHz Level 1: 30~500MHz electromagnetic waves, 1 volt / meter Level 2 : 30~500MHz electromagnetic waves, 3 volts / meter Level 3 : 30~500MHz electromagnetic waves, 10 volts / meter • Electrostatic Discharge ( ESD ) Immunity: 150pF~150Ω Level 1: 2kV Level 2: 4kV Level 3: 8kV • Power Frequency Magnetic Field Immunity: Main Unit: 800A/M Monitor: 80A/M
Electrical performance of RTU devices
1. General electrical characteristics
All power supply equipment, data and control interfaces, communication interface equipment, and human-machine interface equipment in the system shall meet the following general electrical performance requirements: • Insulation resistance: AC circuit external terminals to ground shall have a resistance of 10 MΩ or higher; ungrounded DC circuits to ground shall have a resistance of 1 MΩ or higher . • Insulation strength: Terminals below 500 volts and above 60 volts shall be able to withstand 2000 volts AC for 1 minute between themselves and the enclosure; terminals below 60 volts shall be able to withstand 500 volts AC for 1 minute between themselves and the enclosure ; the inner frame of the cabinet and the cabinet enclosure shall be able to withstand 1000 volts AC for 1 minute.
2. Main anti-interference measures
• It employs input signal matching technology to achieve matching of different signal levels, minimum threshold level of input signals, interference filtering, and suppression of overvoltage surge interference.
• Use photoelectric or electromagnetic isolation to isolate the monitoring system from production equipment and communication equipment.
• Hardware filtering is used to suppress brief pulse interference and prevent false signals.
• Software digital filtering is used to ensure the accuracy of the acquired values and signals.
I/O interface
1. Switch input
• Each digital input port has an LED status indicator; • Input interface parameters: Input method: Dry contact; Contact bounce: 2~30ms
2. Analog Input
• Key analog inputs are displayed on the display panel; (depending on the device model) • Input interface parameters: Signal range: Electrical and non-electrical quantities Current: DC 4~20mA Voltage: DC 0~±5V Temperature: RTD Analog conversion resolution: 11 bits + sign bit Conversion accuracy: not greater than ±0.5% Common mode voltage: 200VDC or AC50Hz
3. Pulse input
• Pulse width > 100ms ; Load capacity > 10mA
Input level: Passive contact or 12VDC/24VDC level
4. Digital Input
Input level: Passive contact or 12VDC/24VDC level
5. Switch output
• The switch output signals use relay outputs. • Each switch output has an LED status indicator. • Switch output interface parameters: Output type: Open contact; Contact capacity: Resistive: 50Hz , 220VAC , 5A ; 220VDC , 0.3A ; Inductive load: 30W
power supply
1. Main control computer
The main control computer (including the host, workstations, and external communication service stations) is equipped with a UPS .
If the AC power is lost, the backup battery should be able to maintain the load for more than 0.5 hours.
Input voltage: AC220V±20%
• Input power frequency: 50Hz±5% • Output voltage: 220V±2% • Output voltage waveform: Power frequency sine wave, 50Hz±1% • Waveform distortion: <3% • Noise: <50dB • High-frequency radiation: No interference • Switching time: Not more than 4ms
2. LCU
The LCU uses an online 1kVA uninterruptible power supply with an input of AC220V±10% .
Grounding
1. Main control unit grounding
The main control level grounding of the computer monitoring system can use the power station's common grounding system, without a separate grounding grid, and its grounding resistance is not greater than 0.5Ω .
2. Terminal grounding
The grounding of each LCU in the monitoring system and the terminal in the central control room of the main plant can only use the power station's common grounding network, and the grounding resistance is not greater than 0.5Ω .
3. Grounding of equipment casing
The equipment enclosure grounding, AC power neutral grounding, DC working grounding, and cable shielding grounding will all use a common grounding terminal in the same cabinet.
