216NG62A main control board HESG441634R1/K HESG216876 multi-function PLC/DCS system actual goods

Description

As an uninterruptible power supply 216NG62A, UPS has been widely used in various industries such as chemical industry, transportation, railway, power plant, substation, metallurgy, nuclear power plant, mobile communication, control equipment and its emergency protection system. It is used to provide continuous, stable and uninterrupted power supply for computers, computer network systems or electronic instruments and meters, such as various transmitters, solenoid valves, etc. The UPS power supply system is mainly composed of the following parts: rectifier for AC/DC conversion, inverter for DC/AC conversion, inverter and bypass output switching circuit, and energy storage battery. As a special power electronic product, UPS will affect the front power supply circuit and the rear load under some abnormal power supply conditions due to its unique circuit characteristics. In this paper, a large area failure of UPS rear stage instrument power board is analyzed to find out the cause, so as to reduce the loss of production caused by similar events.

216NG62A fault phenomenon
On the main frame and expansion frame of the raw material pretreatment unit SIS, power station SIS and generator set CCS in the instrument cabinet room of a company, all the instrument power cards powered by 1 # UPS failed, the air switch corresponding to the upper level power supply tripped, and all the DC power panel outputs disappeared. After the accident, it was found that the varistor MOV1 of 6 power cards inside the instrument had discharge traces.
Through on-site inspection, the UPS supplying power to instrument equipment is three-phase 380VAC input and 220VAC single-phase output. Its output 220VAC is ungrounded. Under normal conditions, the PE of L and N output from the UPS to the earth is 110VAC. Figure 1 is the circuit schematic diagram of the power supply card of the instrument system.
Picture
After the accident, 216NG62A contacted the instrument equipment supplier, who gave the following comments:
TN-S system is required for the AC220V power supply of instrument equipment. The output of UPS is not grounded by TN-S system, which is the reason why the power panel of instrument equipment is burnt out. When the voltage of the power input terminal to the ground fluctuates, the voltage of N terminal and L terminal will rise, causing breakdown of the varistor, short circuit current and tripping of the power supply air switch.
Is this conclusion accurate? Let’s continue the analysis.

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