The present invention discloses a DC converter valve state detection method based on temporal features of converter terminal currents, including the following steps: collecting three-phase AC currents on a converter valve-side of a DC transmission system; defining a current when the currents of two commutating valves are equal as a base value, greater than the base value as a valve conducting current, and less than the base value as a valve blocking current; constructing a valve conducting state by a relative relationship among amplitudes of the three-phase AC currents, and calculating a time interval of each valve conducting state; comparing time intervals of 6 valve conducting states with a time interval of a valve conducting state in normal operation, and determining whether the 6 valve states are normal according to the result of comparison and locating all abnormal valves. The present invention can reliably detect valve states and locate abnormal valves through sequence detection. This method can be applied to actual fault phase judgment and commutation failure judgment, providing a good support for accurate judgment of DC control and protection.

The present invention discloses a DC converter valve state detection method based on temporal features of converter terminal currents, including the following steps: collecting three-phase AC currents on a converter valve-side of a DC transmission system; defining a current when the currents of two commutating valves are equal as a base value, greater than the base value as a valve conducting current, and less than the base value as a valve blocking current; constructing a valve conducting state by a relative relationship among amplitudes of the three-phase AC currents, and calculating a time interval of each valve conducting state; comparing time intervals of 6 valve conducting states with a time interval of a valve conducting state in normal operation, and determining whether the 6 valve states are normal according to the result of comparison and locating all abnormal valves. The present invention can reliably detect valve states and locate abnormal valves through sequence detection. This method can be applied to actual fault phase judgment and commutation failure judgment, providing a good support for accurate judgment of DC control and protection.

A power converter to be tested is supplied with arm current from a hysteresis converter in a state in which it is connected to an auxiliary converter through a line. In the power converter and the auxiliary converter, a circulation operation is performed in which a current path bypassing power storage elements is formed between an output terminal of the power converter and an output terminal of the auxiliary converter, after the start of output of arm current in accordance with a reference current command value in which an AC component and a DC component are superimposed, until a DC component of arm current reaches a predetermined level. After execution of the circulation operation, in the power converter and the auxiliary converter, voltage control of the power storage elements and the output terminals is started.

A power converter to be tested is supplied with arm current from a hysteresis converter in a state in which it is connected to an auxiliary converter through a line. In the power converter and the auxiliary converter, a circulation operation is performed in which a current path bypassing power storage elements is formed between an output terminal of the power converter and an output terminal of the auxiliary converter, after the start of output of arm current in accordance with a reference current command value in which an AC component and a DC component are superimposed, until a DC component of arm current reaches a predetermined level. After execution of the circulation operation, in the power converter and the auxiliary converter, voltage control of the power storage elements and the output terminals is started.

A terminal supporting leakage detection and a detection method for performing leakage detection for the terminal is provided, the terminal may include: a first conductive unit, a second conductive unit, a first access end, and a second access end, wherein the first access end is configured to be connected to a ground line of a main board of the terminal through the first conductive unit and used to access a ground line of an external leakage detection apparatus, and the second access end is configured to be connected inside the terminal to a metal portion of a outer casing of the terminal through the second conductive unit and used to access a leakage test line of the leakage detection apparatus.

A terminal supporting leakage detection and a detection method for performing leakage detection for the terminal is provided, the terminal may include: a first conductive unit, a second conductive unit, a first access end, and a second access end, wherein the first access end is configured to be connected to a ground line of a main board of the terminal through the first conductive unit and used to access a ground line of an external leakage detection apparatus, and the second access end is configured to be connected inside the terminal to a metal portion of a outer casing of the terminal through the second conductive unit and used to access a leakage test line of the leakage detection apparatus.

A burn-in chamber is provided, configured to provide the required temperature for a device under test (DUT), including a side wall, a guiding plate, an air flow plate, a partition assembly, and a fan. The air flow plate has a ventilation structure, and the guiding plate is located between the side wall and the air flow plate. The partition assembly is disposed on both sides of the air flow plate. The partition assembly and the air flow plate together form an accommodating space for accommodating the DUT. The partition assembly forms a return channel with respect to the other side of the accommodating space with the side wall. When the fan is active, air from the accommodating space passes through the air flow plate and is guided to the return channel via the guiding plate, and air is returned to the accommodating space through the return channel.

A burn-in chamber is provided, configured to provide the required temperature for a device under test (DUT), including a side wall, a guiding plate, an air flow plate, a partition assembly, and a fan. The air flow plate has a ventilation structure, and the guiding plate is located between the side wall and the air flow plate. The partition assembly is disposed on both sides of the air flow plate. The partition assembly and the air flow plate together form an accommodating space for accommodating the DUT. The partition assembly forms a return channel with respect to the other side of the accommodating space with the side wall. When the fan is active, air from the accommodating space passes through the air flow plate and is guided to the return channel via the guiding plate, and air is returned to the accommodating space through the return channel.

Systems and methods for direct heater diagnostics for a hot melt liquid dispensing system are disclosed. At least one of a current measurement or a voltage measurement is received from a respective current and/or voltage sensor positioned at an electrical circuit that supplies electric power to a heater associated with the dispensing system. The heater can be for an applicator or heated hose attached to the dispensing system, a melter of the dispensing system, or a pump of the dispensing system. A state of the electrical circuit is determined based on the at least one of the current or voltage measurement.

Systems and methods for direct heater diagnostics for a hot melt liquid dispensing system are disclosed. At least one of a current measurement or a voltage measurement is received from a respective current and/or voltage sensor positioned at an electrical circuit that supplies electric power to a heater associated with the dispensing system. The heater can be for an applicator or heated hose attached to the dispensing system, a melter of the dispensing system, or a pump of the dispensing system. A state of the electrical circuit is determined based on the at least one of the current or voltage measurement.