With the rapid improvement of ship automation, uninterruptible power supply equipment is more and more widely used on ships, and its importance is self-evident. However, ships operate in harsh marine environments, and their power network systems are at great risk of insulation failures. In order to ensure the stable operation of the ship's power system, the IT system is widely used in the ship's power supply, which is a low-voltage power distribution network that is not grounded at the neutral point or grounded with high resistance.
According to the provisions of international standards such as IEC, when the first single-phase ground fault occurs in the IT system or the insulation resistance is lower than the preset value, the system can still continue to operate, but at this time, the insulation monitor will send out an alarm signal in time to remind the staff to deal with it.
In the current ship power network system, there are a variety of insulation detection methods, including DC superposition method, single frequency method, dual frequency method, "S" injection method and zero sequence current method. Among these methods, although the DC method can monitor the insulation of the entire power grid, it cannot accurately determine the fault of the specific line, and the transformer needs to be installed to select the line, and the distributed capacitance of the system cannot be measured. The dual-frequency method requires two different frequency detection signals to be fed into the grid, which makes the entire detection network extremely complex and greatly reduces the reliability of the detection equipment. The "S" injection rule is mainly used to judge the single-phase ground fault of the power grid, and it is powerless to solve the insulation problem of the entire power network.
In contrast, the single-frequency method stands out for its concise principle and efficient functionality. It can not only measure the insulation resistance and distributed capacitance of the system at the same time, but also overcome the disadvantages such as the complexity of the dual-frequency frequency conversion control device, and become a practical and reliable insulation detection method for ship power networks.
Ship insulation** monitoring solutions
Insulation monitoring and insulation fault location products.
AIM-T series industrial insulation monitor.
AIM-T series insulation monitors are mainly used in IT power distribution systems in industrial sites, mainly including AIM-T300, AIM-T500 and AIMT500L, all of which are suitable for pure AC, pure DC and AC and DC hybrid systems.
Among them, AIM-T300 is suitable for AC, DC and AC/DC hybrid systems below 450V, and AIM-T500 is suitable for AC, DC and AC/DC hybrid systems below 800V. Compared with AIM-T500, the AIM-T500L has an additional insulation fault location function.
Insulation fault location products.
Industrial insulation fault location products are used with AIM-T500L insulation monitor, mainly including ASG200 test signal generator, AIL200-12 insulation fault locator, AKH-066L series current transformer is suitable for IT power distribution system with many outgoing circuits.
Insulation monitoring coupler.
The insulation monitoring coupling meter is used with AIM-T500 insulation monitor, mainly including ACPD100 and ACPD20
It is suitable for IT power distribution systems with AC voltage higher than 690V and DC voltage higher than 800V.
Field Application** Reference.