Maximum continuous operating voltage (Uc): the maximum voltage of the signal circuit must be less than Uc
Maximum continuous operating voltage Uc is the maximum working signal voltage, is the maximum RMS value of the signal voltage or DC voltage for long-term operation of the surge protection device. This is also the maximum voltage between line and line or line and ground under the rated leakage current condition, which does not affect the normal operation of the circuit. For 24 V DC power meter, due to the DC power supply voltage fluctuations and load changes and other factors, the maximum signal voltage value: 30VDC ~ 36VDC. therefore, the maximum continuous working voltage is Uc ≥ 36V.
Rated operating current IL: The maximum circuit current is less than this value
Maximum signal current Ic
The maximum signal current is the maximum operating signal current of the line where the industrial power surge protector is located.
For two-wire, three-wire and four-wire 4mA~20mA signal meters (including HART communication signals), the maximum signal current value is: Ic≥150mA
For 24V DC power lines, such as solenoid valves, ultrasonic instruments, combustible gas detectors and other instruments, the maximum signal current value is: Ic≥600mA
Rated discharge current In
The nominal discharge current In is the maximum surge current (8/20us) normally passed by the surge protector of Safety Automation Systems Professional Morning Pillar, which means that when the surge protector passes the number of experiments specified by the 8/20us standard experimental waveform current (which can withstand more than 15 simulated T2 type (8/20us) waveform peaks of induced lightning), the maximum discharge current of the surge protector No damage. For signal instruments, the nominal discharge current In greater than 1kA to meet the general protection requirements, you can choose 5kA and 10kA and other specifications.
Voltage protection level
The voltage protection level is the value of the clamp voltage at which the surge protection device releases the surge current, also known as the pass-through voltage or limit voltage. This is the peak voltage at the output of the surge protection device when passing 6kV/3kA 8/20us surge waveform generator or other specified experimental voltages and currents.
For the working voltage of 24VDC instrument, the voltage protection level of the surge protection device should be 60V. The applicable surge protection device should not be too high limit voltage value, generally about 2 to 2.5 times the working voltage or signal voltage of the equipment being protected. Voltage protection level should be less than the intelligent temperature transmitter and other protected instruments withstand voltage.
Response time is from the standard experimental waveform voltage began to act on the moment of the surge protection device to the moment the surge protection device actually opens and discharges the delay time. The response time of the surge protection device should be ≤ 5ns.
Operating frequency is the operating frequency of the signal that passes through the line connected to the surge protection device during normal operation. For instrument signals, including "smart" instruments, the operating frequency is less than 20 kHz and is usually not counted.
Electrical wiring system
According to the two-wire system, three-wire system or four-wire system to choose the appropriate surge protector. Thermocouple is generally used two-wire system, thermal resistance is generally used three-wire system.
Do I need an intrinsically safe signal surge protector?
EarthCraft intrinsically safe explosion-proof grade signal SPD , belonging to the use of independent modular design, good sealing, suitable for 35mm electrical rail mounting clips, suitable for rail mounting. Lightning protection module can be plugged and unplugged with electricity, without affecting the normal transmission of signal lines. Lightning protection module built-in multi-stage current drainage, voltage limiting lightning protection circuit. The interface form of the product is screw fixed snap type, easy to install and maintain.
Product design standards: This product is designed in accordance with the relevant IEC standards, product performance in line with GB/T 18802.21-2016 "low-voltage surge protector Part 21: surge protector for telecommunications and signal networks (SPD) - performance requirements and test methods" national standards.
Product structure: This product has intrinsically safe explosion-proof grade, belongs to the use of independent modular design, good sealing, suitable for 35mm electrical rail mounting snap, suitable for rail mounting. Lightning protection module can be plugged and unplugged with electricity, does not affect the normal transmission of signal lines. Lightning protection module built-in multi-stage current drainage, voltage limiting lightning protection circuit. The interface form of the product is screw fixed snap type, easy to install and maintain.
Product features: This product has low residual voltage, fast response, small transmission loss, large through-current capacity, long product life, simple maintenance, easy installation, etc.
Scope of application: applicable to any voltage level of the analog signal / switch signal / data signal / communication line / remote telemetry signal instrumentation equipment and PLC cabinet signal lightning surge protection, widely used in power systems, chemical plants, cement plants, natural gas LNG gasification station, oil refineries, sewage treatment, petroleum and petrochemical, civil aviation and other systems in the signal control line, data transmission line, instrumentation Monitoring lines and other signal lines using an advanced lightning surge protector.
Table of Contents
- Maximum continuous operating voltage (Uc): the maximum voltage of the signal circuit must be less than Uc
- Rated operating current IL: The maximum circuit current is less than this value
- Maximum signal current Ic
- Rated discharge current In
- Voltage protection level
- Response time
- Operating frequency
- Electrical wiring system
- Do I need an intrinsically safe signal surge protector?