Recently, many customers have been asking the YiZao customer service team about the key parameters of surge protectors, looking to review the specific specifications of YiZao surge protectors. It seems that there is still some uncertainty regarding the parameters indicated on surge protectors. In this article, the YiZao editor will provide a detailed introduction to several key parameters of YiZao surge protectors.
1. Definition of Surge Protectors
Surge Protective Device (SPD): An electrical device used to limit transient overvoltage and discharge surge currents. It contains at least one non-linear component.
2. Key Parameters of Surge Protectors
One-port SPD: An SPD connected in parallel with the protected circuit. It separates the input and output terminals, without any special series impedance between them.
Two-port SPD: An SPD with two sets of input and output terminals, featuring special series impedance between these terminals.
Figure 1-1: Interpretation of Surge Protector Parameters
Maximum Discharge Current (Imax): The peak current with an 8/20 waveform that passes through the SPD, determined according to the II class test procedure. Imax is greater than In.
Nominal Discharge Current (In): The peak current with an 8/20 waveform for II class tests passing through the SPD.
Impulse Current (Iimp): Defined by three parameters: Peak current (Ipeak), charge quantity (Q), and specific energy (W/R). Tests should follow the load operation test procedure for class I SPD categorization.
Voltage Protection Level (Up): A parameter characterizing the voltage-limiting performance between SPD terminals. It can be selected from a list of preferred values and should be greater than the maximum limiting voltage value.
Limiting Voltage (Um): The maximum voltage peak measured between the SPD terminals when a specified waveform and amplitude is applied.
Maximum Continuous Operating Voltage (Uc): The highest AC RMS voltage or DC voltage that can be continuously applied in the SPD protection mode. This value should be significantly higher than the rated voltage (Un).
System’s Nominal Voltage (Un): The nominal voltage of a system relative to the ground.
Temporary Overvoltage Test Value (UT): The test voltage value applied to the SPD under TOV conditions, lasting for a specified time (tT).
Enclosure Protection Rating (IP): Represents the degree of protection provided by the enclosure against access to hazardous parts, and ingress by solid objects and water.
Residual Voltage (Ures): The voltage peak between SPD terminals when discharge current flows through it.
Rated Short Circuit Current (ISCCR): The maximum expected short circuit current rating used to assess the power system for the SPD and the connected specifier.
Follow Current (If): The current flowing into the SPD from the power source after an impulse discharge.
According to the GB T18802.11 standard 7.1.1, it should be marked on the SPD body or permanently labeled on it:
(1) Manufacturer’s name or trademark and model; (2) Maximum continuous operating voltage (Uc) for each protection mode; (3) Current type: ac or “~” and/or frequency; (4) Voltage Protection Level (Up) for each protection mode; (5) Enclosure Protection Rating (when IP > 20); (6) Tests declared by the manufacturer for each protection mode:
- Class I test: “Class I test” and “Iimp” with values in kA, and/or “T1” (in a square) and “Imp” with values in kA;
- Class II test: “Class II test” and “In” with values in kA, and/or “T2” (in a square) and “In” with values in kA;
- Class III test: “Class III test” and “Uoc” with values in kV, and/or “T3” (in a square) and “Uoc” in kV.
By now, you should have a certain level of understanding of the parameters of surge protectors. When selecting surge protectors, it is crucial to grasp these key parameters to ensure better compatibility with the circuit equipment.