202 results about "Insulation monitoring device" patented technology

The invention provides an insulation monitoring device which is used for monitoring ground insulation conditions of high voltage direct current power source direct current output voltage, judging insulation conditions through insulation resistance of monitoring bus-bar to the ground, and uploading values of the insulation resistance to an upper computer. The insulation monitoring device comprises a first additional delivering resistor R1, a second additional delivering resistor R2, a first delivering switch K1 and a second delivering switch K2. The R1 is in series connection with the K1. One end of the R1 is connected to a positive bus-bar. The other end of the R1 is connected to the ground. The R2 is in series connection with the K2. One end of the R2 is connected to a negative bus-bar. The other end of the R2 is connected to the ground. Equivalent ground insulation resistance of the positive bus-bar is R+. Equivalent ground insulation resistance of the negative bus-bar is R-. The R+ and the R- are obtained in a detected mode through an unbalanced bridge method. Due to adoption of the unbalanced bridge method, conditions of any insulation such as ground insulation of a bus-bar monopole, bus-bar twin poles, a monopole of the same branch, twin poles of the same branch, monopoles of different branches and twin poles of the different branches can be monitored, and any insulation condition can not be omitted. Due to build of a branch monitoring equation, insulation conditions can be timely and accurately monitored.

The invention discloses an insulation monitoring device and method of a power cell of an electric vehicle. The insulation monitoring device comprises an electricity leakage detection circuit, a microprocessor, a signal generator and a signal collector, wherein the signal generator is connected with the chassis of the electric vehicle and the signal collector is connected with a sampling resistor. The signal generator is used for generating low-frequency voltage signals, and the signal collector is used for collecting voltage signals on the sampling resistor and transmitting the voltage signals to the microprocessor through a signal conditioning circuit; because the current flowing through the sampling resistor is the sum of the leakage current of the high-voltage system of the power cell and current generated by a low-frequency voltage signal transmitted by the signal generator, the microprocessor calculates an insulation resistance of a high-voltage system of a power cell on the chassis of the electric vehicle according to a current variation value; and when the insulation resistance of the high-voltage system of the power cell on the chassis of the electric vehicle is reduced to a preset response value, the microprocessor drives an alarming device to open and reminds a user to quickly carry out fault diagnosis, therefore ensuring the regular operation of the power cell and avoiding the potential safety hazard due to drop of insulation.

The implement of the invention relates to the field of an electric power system, particularly relates to a direct current system insulation monitoring method and a direct current system insulation monitoring device, and is used for solving the problem in the prior art that in the monitoring of a direct current system, the time consumption of the branch routing inspection process is large, so that the faulted branch can not be detected in time. The direct current system insulation monitoring method provided by the implement of the invention comprises the steps of determining a to-be-detected pole of the branch connected with a faulted bus when the bus faults, and detecting the to-be-detected pole of the branch, wherein the insulation resistance value of the bus connected with the to-be-detected pole is not large than a first threshold. The direct current system insulation monitoring method and the direct current system insulation monitoring device provided by the implement of the invention can determine the to-be-detected pole of the branch connected with the faulted bus when the bus faults, and detect the to-be-detected pole of the branch so as to determine the faulted branch, so that the negative pole and the positive pole of each branch are not required to be inspected every time the bus faults, thereby greatly shortening the time for detecting the faulted branch.

The invention provides a high-voltage DC insulation monitoring device for monitoring the insulation resistance value of a high-voltage DC bus to a reference ground in real time. The device comprises two current-limiting resistors, a sampling resistor, a coupling resistor, a signal generation unit, a control unit and a power source unit, wherein the ontrol unit comprises an instruction subunit, a sampling subunit and a calculating subunit; the instruction subunit is used for outputting a control instruction to the signal generation unit; the signal generation unit is used for outputting a low-frequency measuring signal after receiving the control instruction; the low-frequency measuring signal respectively, after traveling through the coupling resistor, an insulation resistor and the two current-limiting resistors, returns to the signal generation unit through a sampling resistor flow; the sampling subunit is used for performing analog-to-digital conversion on the voltage signal of the sampling resistor; and the calculating subunit is used for calculating a conversion result to obtain the insulation resistance value. Correspondingly provided is an electric automobile. The high-voltage DC insulation monitoring device can dynamically monitor the insulation performance of the electric automobile in real time.

The invention discloses a detection device and a detection method for a station-dedicated DC power system insulation monitoring device. The detection device comprises a DC power unit, an auxiliary DC power unit, and an AC power unit, wherein the DC power unit comprises a first rectifying voltage-regulating module SDC1 and a DC busbar KM1; the auxiliary DC power unit comprises a second rectifying voltage-regulating module SDC2 and an auxiliary DC busbar KM2; the AC power unit comprises an AC voltage regulator T1 and a change-over switch S2; the detection device further comprises a ground insulation testing unit, and a waveform measuring and recording, AC jump and control protection circuit. The detection device has the benefits as follows: mutual jump alarm test, ring network alarm test, AC jump alarm test, balanced bridge AC superimposition resistance test, insulation resistance monitoring, grounding line selection correctness test and other function and performance detection or tests and verifications for the station-dedicated DC power system insulation monitoring device are realized, so as to prevent the improper DC power supply insulation monitoring device from influencing the safe production of a power system.

A device and method is for insulation monitoring in a power supply system composed of a main system including a neutral point that is high-resistance grounded via a neutral-point resistance and, optionally, of at least one subsystem, wherein the main system and the subsystem each have a differential current measuring device for registering a differential current. The invention is based on feeding a measuring signal into the optionally branched HRG system via an active measuring method and registering the fault current driven by the measuring signal in the outgoing power feeds to be monitored by means of a differential current measurement and using the registered fault current in an evaluating device to determine the total insulation resistance of the power supply system and to determine the partial insulation resistances of the main system and potentially present subsystems. Furthermore, the insulation monitoring device can be employed for insulation fault location.

The invention discloses a train and an insulation monitoring device and method thereof. The device comprises a first subcircuit, a second subcircuit, a bidirectional power supply, a current detector, and an insulation monitoring device. The first subcircuit having a first resistor is connected with one pole of a train high-voltage loop. The second subcircuit connected with a train body has a second resistor. The bidirectional power supply is connected with the first subcircuit and the second subcircuit. The current detector is used for detecting a first current flowing through the second resistor when the bidirectional power supply works in a first direction and is used for detecting a second current flowing through the second resistor when the bidirectional power supply works in a second direction The insulation monitoring device is used for obtaining an insulation resistance value of the train according to the resistance value of the first resistor, the resistance value of the second resistor, the detection value of the first current, and the detection value of the second current. Therefore, the insulation resistance changing situation of the train can be monitored in real time. Moreover, the circuit structure becomes simple and the operation becomes convenient; and the security of the train can be improved.

The invention discloses a system for intelligently monitoring state information of a transformer. The system comprises a universal measurement device, a gas-in-oil monitoring device, a transformer partial discharge monitoring device, a sleeve insulation monitoring device, an iron core grounding current monitoring device, an exchanger and a processor, wherein each monitoring device is respectively connected with the processor through marking interfaces of the exchanger to transmit monitored various signals of the transformer to the processor for analyzing and processing; the processor is used for carrying out fault diagnosis and risk evaluation on the operating condition of the transformer on the basis of a preset transformer fault diagnosis algorithm and gives an alarm when a fault is occurred; meanwhile, a standard communication protocol, namely, an IEC61850 protocol, is adopted between each monitoring device and the processor. The system and a method have comprehensive monitoring parameters, are easy for integration and have strong independence.

The invention relates to a device for automatically isolating and positioning earth faults of a Dc system, which overcomes the defects that the conventional device can only monitor specific earth-return circuits or branch circuits of a DC return circuit earth, but cannot isolate fault return circuits from the DC system so as to influence safe operation of normal return circuits because of fault operation of the fault return circuits. The device supplies power to power consumption units by using mutually independent dual DC power supplies and switches fault branch circuit power units from a common power supply to an isolated power supply. All the branch circuits are provided with on-line insulation monitoring device; a communication module is connected with the insulation monitoring device; output signals are connected with an upper PC machine; and the upper PC machine controls all the branch circuits to be isolated sequentially so as to find fault points, receives, stores and comprehensively analyzes monitoring data of all the branch circuits, reports the earth faults of the DC system and displays earth return circuit numbers and earth points in the branch circuits.

The present invention relates to a partial discharge sensor for a high-voltage insulation monitoring device comprising a housing and located in the housing a measurement circuit for measurement of partial discharges in a high voltage system to be tested and a coupling capacitor having one electrode connected to the measurement circuit and the other electrode to a first high voltage conductor to be connected to a high voltage line of the system to be tested, wherein it further comprises a calibration circuit located in the housing and comprising a calibration capacitor having one electrode connected to the calibration circuit and the other electrode connected to said first or a second high voltage conductor to be connected to a high voltage line.

A charging pile insulation monitoring device designed using a special bridge method comprises a balanced bridge module, an unbalanced bridge module, a voltage conversion module, a voltage isolation module, a signal processing module and a communication module, which are connected in sequence. The balanced bridge module is composed of a pair of resistors of positive power-ground and a pair of resistors of negative power-ground. The voltage collected by the voltage conversion module is taken from partial voltages of the two pairs of resistors. The voltage isolation module is used for converting an input voltage into a low voltage signal. The signal processing module digitally transforms the input voltage, and calculates the value of grounding resistance. The communication module is used for sending the calculation result to a system host. With the device, the fault type of charging pile grounding can be inferred, and the value of grounding resistance can be calculated accurately. The charging pile insulation monitoring device based on the monitoring method can stably and reliably monitor the grounding fault of a DC charging pile and the size of grounding resistance. The monitoring method is relatively advantageous in the field at present.

The invention relates to an insulation fault locating system using branch-selective feeding and to a selective insulation monitoring system for a branched IT system composed of multiple subsystems. For insulation fault location, a differential current measuring device, a test signal generator and a blocking device are arranged in each subsystem. The insulation monitoring device additionally comprises a selective decoupling device arranged in each subsystem. Furthermore, the invention relates to a method for determining a cross impedance between two subsystems on the basis of the insulation monitoring system according to the invention.

The invention relates to a ground fault simulation device for an electric power direct current system. The ground fault simulation device for the electric power direct current system comprises rotary switches SA1-SA4, resistors R1-R18, capacitors C1-C14, an adjustable transformer T and an alternating current 220V power supply GJ. The ground fault simulation device for the electric power direct current system has the advantages that complex ground faults of various types can be simulated flexibly and safely by using a direct current bus or direct current branches of a field direct current power supply system, and the ground fault simulation device is convenient to mount and operate; alternating current invasion simulation can be further carried out on the direct current bus or all the direct current branches, alternating current electricity jumping faults such as PT alternating current voltages and 380V alternating current low voltages in an electric power system can be simulated, and alternating current measuring and recording functions of an insulation monitoring device can be detected; an interlocking method is adopted by the rotary switches in the ground fault simulation device, and the safety and the reliability in the ground fault simulation process are ensured.

The invention provides an intelligentized switch cabinet monitoring system. The intelligentized switch cabinet monitoring system comprises a linear displacement sensor, a magnetic balance type hall current voltage sensor, an infrared video monitoring device, an acoustic surface wave temperature measuring device, an insulation monitoring device and a control system; the linear displacement sensor is connected with a movable contact insulating pull rod of a circuit breaker, the magnetic balance type hall current voltage sensor is connected with an opening and closing coil circuit of the circuit breaker, the infrared video monitoring device, the acoustic surface wave temperature measuring device and the insulation monitoring device are all arranged in the switch cabinet, the linear displacement sensor, the magnetic balance type hall current voltage sensor, the infrared video monitoring device, the acoustic surface wave temperature measuring device and the insulation monitoring device are all connected with the control system. The invention further provides an intelligentized switch cabinet monitoring method. According to the system and the method, the mechanical characteristic parameter of the circuit breaker in the switch cabinet, data of real-time image, temperature, insulation and the like of main devices in the switch cabinet can be accurately acquired in an online manner, and the control system can give an alarm in time when abnormal conditions are discovered.

The invention relates to a direct current insulation monitoring method which comprises sampling resistors, large-resistance resistors, small-resistance resistors and switching tubes. The large-resistance resistors, the small-resistance resistors and the sampling resistors are connected in series between an anode and the ground and between a cathode and the ground respectively, and the two small-resistance resistors are connected in parallel with the switching tubes respectively. Insulation resistance values of the anode and the cathode can be obtained by making and breaking the two switching tubes respectively, measuring voltage values across the sampling resistors and making calculation on the measured values. The method has the advantages that with the adoption of the low-voltage switching tubes, quick making and breaking can be achieved, the measurement speed is high, the cost is lower, and the influence of a ground capacitor in a system is small, so that the robustness and measurement precision are high. The invention further provides a direct current insulation monitoring device.

The invention relates to insulation monitoring of a direct current system, and particularly relates to an instant alternating current invasion prevented insulation monitoring device. The device comprises a host, a wire selection device and a direct current leakage current sensor, wherein the host comprises a CPU data processing module, a data collection module, a balance bridge and unbalanced bridge circuit module, a power supply module, a display module, an alarm module and a communication module; the CPU data processing module is connected with the data collection module; the data collection module comprises a multi-channel collection electronic switch, an operational amplifier and a high-precision AD chip, and is used for collecting positive and negative earth grounded voltage of a direct current bus and voltage of the direct current bus in real time; the balanced bridge and unbalanced bridge circuit module comprises a group of balanced bridge resistor and a detection bridge resistor; the display module and the alarm module are connected with the CPU data processing module; and the wire selection device is connected with the CPU data processing module and the direct current leakage current sensor.

The invention provides a bridge used for a direct current insulation monitoring device and a running method of the bridge used for the direct current insulation monitoring device. The bridge comprises a balanced bridge and a detection bridge, wherein the balanced bridge is composed of a balanced resistor R1 and a balanced resistor R2, wherein the balanced resistor R1 is connected between a bus positive pole and the earth, and the balanced resistor R2 is connected between a bus negative pole and the earth. The detection bridge is composed of a detection resistor R3, a detection resistor selector switch K1 and / or a detection resistor R4 and a detection selector switch K2, wherein the detection resistor R3 and the detection resistor selector switch K1 are connected between the bus positive pole and the earth, and the detection resistor R4 and the detection resistor selector switch K2 are connected between the bus negative pole and the earth. For the detection resistor R3 connected between the bus positive pole and the earth and the detection resistor R4 connected between the bus negative pole and the earth, at least one of the R3 and the R4 is changeable and controllable. The bridge used for the direct current insulation monitoring device has the advantages of carrying out insulation monitoring by utilization of the detection bridge with the changeable resistor, being capable of changing the resistance value of the detection bridge in a self-adaptation mode according to direct earth capacitance and insulation resistance of a direct current system and taking safety of the direct current system and accuracy of insulation resistance measuring into account.

The invention discloses a downhole power cable insulation monitoring device comprising a low-frequency voltage source, first to fourth inductors, a Hall current sensor, a signal conditioning circuit, an A / D converter, a processing module, a display module, an alarm, and a communication module. The processing module comprises a processing unit and a determining unit. The signal conditioning circuit comprises a wave trap circuit, a filtering circuit, an amplification circuit, and a rectification circuit. The wave trap circuit comprises first to fourth resistors, a first capacitor, a second capacitor, and an operational amplifier. The downhole power cable insulation monitoring device may online monitor the insulation state of a cable in real time, improves coal mine power supply continuity, reliability and security, achieves high sensitivity and low errors, and timely notifies downhole and ground workers for carrying out handling so as to guarantee operation safety and prevent economic losses.

The invention provides an insulation monitoring device for an electric vehicle, which includes an electric vehicle power system and an insulation monitoring module, wherein the insulation monitoring module includes a first resistor, a second resistor, a first detection control port, a second detection control port, a first diode, a second diode, a first detection power supply and a second detection power supply. Two insulation detection points are arranged in a return circuit of the electric vehicle power system, and the insulation monitoring module is used for detecting the insulating resistance between the insulation detection points and the vehicle body, thereby confirming the insulation condition of a power high-voltage system, and further guaranteeing the security of the system.

The invention relates to a direct current insulation monitoring device and a method capable of compensating deviation of voltage to earth of a positive pole and a negative pole. The device comprises a balanced bridge circuit, an unbalanced bridge circuit and a compensation bridge circuit. The compensation bridge circuit inputs resistance to the direct current bus negative pole voltage to earth or the direct current bus positive pole voltage to earth according to the deviation conditions of voltage to earth of the positive pole and the negative pole of a direct current system, so the direct current bus positive pole voltage to earth and the direct current bus negative pole voltage to earth are almost the same or achieve safe operation conditions of the direct current system. When the direct current bus voltage to earth deviates, the deviated voltage can be compensated through the compensation bridge circuit to enable the positive pole voltage to earth and the negative pole voltage to earth of the direct current system to be under a balanced state, and therefore a relay protection maloperation problem caused by the single point grounding of the positive pole of an exit relay is avoided.

The invention relates to a method and a system for monitoring the insulation level of a substation power cable, which comprises a power cable insulation monitoring device based on an optimized direct current superposition method. A power cable insulation monitoring system is built based on the power cable insulation monitoring device. According to the power cable insulation monitoring device based on the optimized direct current superposition method, the same direct current voltage source is connected onto three phases of lines of a high-voltage bus respectively through three equivalent megohm-level current-limiting resistors, current is detected and sampled, a blocking capacitor is matched for use, the blocking capacitor is hooked between the primary-side neutral point of a voltage transformer and the ground, and when the insulation level of the power cable drops, the direct current can have a unique channel to conveniently and accurately calculate the direct current resistance. According to the method and the system of the invention, as the system is provided with the power cable insulation monitoring device based on the optimized direct current superposition method and the power cable insulation monitoring system is built, power cable insulation drop judgment based on the insulation monitoring system can be carried out.

The invention discloses an insulation monitoring device based on a non-balanced bridge for a direct current system and belongs to the technical field of ground insulation monitoring of buses of directcurrent systems. The device mainly solves the problem that the adaptive capability cannot be achieved in existing measurement and the measurement reliability cannot be ensured. The device is mainly characterized by comprising a first branch circuit, a second branch circuit, a main control single chip microcomputer, a signal conditioning circuit and a switch array, wherein the signal conditioningcircuit and the switch array are connected with the main control single chip microcomputer; the first branch circuit is in parallel connection with the second branch circuit, and the two ends of the first branch circuit are connected with a sixth switch and a seventh switch respectively; the junction point between a first switch and a third sensor and the junction point between a second switch anda fourth sensor are both connected with a fifth switch; a first sensor, a second sensor, the third sensor and the fourth sensor are electrically connected with the signal conditioning circuit; the signal conditioning circuit is also connected with a fifth sensor; the switch array is electrically connected with the first switch, the second switch, a third switch, a fourth switch, the fifth switch,the sixth switch and the seventh switch separately. The device is mainly applied in insulation resistance of positive and negative electrodes of direct current systems on low-voltage ground (case ground) in BMSs or high-low voltage direct current systems with similar demands.

The invention relates to a direct-current insulation monitoring device. The device comprises a balance bridge circuit and an unbalanced bridge circuit. The monitoring device further comprises an intelligent adjusting circuit and a current leakage sensor. The intelligent adjusting circuit comprises a controlled current source and a switching device used for connecting the controlled current source between a positive bus-bar and the ground or between a negative bus-bar and the ground. The current leakage sensor is connected with a detection switch in series and then connected to the controlled current source in parallel. The controlled current source in the intelligent adjusting circuit can simulate unbalanced failures, and when the unbalanced failures occur, the current leakage sensor will detect current leakage and then calculate resistance, to the ground, of the positive bus-bar and the negative bus-bar. By the adoption of the monitoring device, the failures can be simulated and detected, and therefore failures of equipment can be prevented.

The invention discloses a vehicle high-voltage DC system insulation monitoring device and a monitoring method, which can compatibly meet insulation performance detection requirements of the system ina state with high-voltage power or without high-voltage power, can perform internal self detection through a built-in standard resistor before the insulation detection function of the system is enabled, can confirm the effectiveness of the insulation detection function and can thus avoid leakage alarm and false alarm of the insulation monitoring device. When the system has no high-voltage power, apositive bus and a negative bus are respectively connected to an insulation detection circuit through a switch, and the standard resistor with the closest resistance range is selected to accurately measure the resistance of an equivalent insulation resistor. When the system has high-voltage power, two circuit states are made through two built-in standard resistors and the series switch, and basedon two measurement results, the overall parallel value of an equivalent insulation resistor of the positive bus to a vehicle body shell and an equivalent insulation resistor of the negative bus to the vehicle body shell is calculated. Based on the measurement result of the insulation resistor, the vehicle insulation performance is evaluated.

The invention discloses a method and a device for monitoring the crossing of direct current insulated buses. The method comprises the following steps of arranging two sections of independently running direct current buses on two direct current ground insulation monitoring devices respectively; performing connection according to a direct current crossing mode, inputting the balanced bridge resistance of the two direct current ground insulation monitoring devices into the other direct current ground insulation monitoring devices, and monitoring the ground resistance of each other by using the direct current ground insulation monitoring devices; arranging a group of communication cables between the two respectively running direct current ground insulation monitoring devices for data communication; receiving related measurement data acquired by acquisition modules through the communication cables by using the two direct current ground insulation monitoring devices respectively; judging whether direct current crossing corresponding to the direct current bus crossing mode occurs or not according to the measurement data. According to the method and the device, whether the direct current crossing occurs or not can be accurately monitored, an alarm about a direct current line to which the direct current crossing occurs is given, and a loop in which the two sections of direct current buses are crossed can be accurately found.

The invention relates to a direct current insulation monitoring device. The device comprises an intelligent adjusting circuit, and the intelligent adjusting circuit comprises a controlled current source and a switching device used for connecting the controlled current source between a positive bus-bar and the ground or between a negative bus-bar and the ground. The vector sum of current flowing through balance bridge resistors to the ground is detected in real time, if the vector sum of the current is plus, the controlled current source is connected with the positive bus-bar, if the vector sum of the current is minus, the controlled current source is connected with the negative bus-bar, and then the voltage, to the ground, of the positive bus-bar and the negative bus-bar is adjusted. In this way, it is prevented that when an unbalanced bridge is switched, the fluctuations of the voltage, to the ground, of the positive bus-bar and the negative bus-bar of the insulation monitoring device cause false action of an exit relay.

The invention relates to an insulation monitoring method for an IT (Isolation Terre) electric system insulation with a neutral conductor. The monitoring method comprises the following steps of: bunching a direct current signal source DC (direct current) and a voltage V on the neutral point of a distribution transformer, and connecting a sampling resistor R in series; and when measuring that a direct current I= of the serial sampling resistor R exists and is greater than one threshold, proving that the insulation of one phase is subjected to deterioration, and reacting the variation of the serial direct current I=. According to the invention, a simple method can be used for monitoring an insulation fault on the neutral conductor of an IT electric system, and the specific resistance value of an earthing resistor is obtained.

The invention discloses a monitoring device and method, and particularly relates to an insulation monitoring device and method for a DC system. The insulation monitoring device and method for the DC system is especially applied to insulation monitoring and locating when AC jumps into the DC system. The insulation monitoring device comprises a first CPU, a second CPU and a third CPU. The first CPU is connected with the second CPU through a dual-port RAM, the second CPU is connected with the third CPU through an RS 458 port, the first CPU is connected with a first sampling circuit and a DC voltage input circuit, the second CPU is connected with a liquid crystal display circuit and a memorizer, and the third CPU is connected with a second sampling circuit and a branch sensor input circuit. When a fault that the AC jumps into the DC system happens to the DC system, the monitoring device can be used for monitoring the insulation resistance of the DC system, locating a fault branch and calculating AC input impedance of the branch which the AC jumps into; when the fault that the AC jumps into the DC system does not happen, the insulation monitoring device can be used for monitoring the insulation resistance of the DC system and locating an insulation lowering branch, and is favorable for field staff to maintain the DC system for safety running.

The invention provides a switching type insulation monitoring error self-adapting method based on voltage prediction. The method comprises the steps as follows: a self-calibration circuit comprising a calibration switch and a calibration resistor connected in series mutually is connected between the ground and a positive pole as well as between the ground and a negative pole of a bus in a switching type insulation monitoring device respectively; after the calibration switch is switched off, an error self-calibration mode is entered; bus voltage is measured and voltage to ground of the positive pole (negative pole) of the bus is collected for 3 times at a first preset time interval of (delta t1) minutes, and accordingly, the voltage to ground of the positive pole (negative pole) of the bus is calculated; insulation resistance to ground is calculated according to obtained parameters; after the calculating time of the insulation resistor reaches a preset time, whether the error between equivalence insulation resistance to ground of the positive pole and the negative pole of the bus with a preset number group and the known calibration resistance is in a reasonable range is analyzed; if the error is not in the reasonable range, a time definite value is added and taken as a new delta t1, and the steps are repeated; and if the error is in the reasonable range, the delta t1 is stored, and the calibration switch is switched off, so that the stored delta t1 enters a normal insulation resistance monitoring mode.

The invention discloses a device and method for searching for a loop channeling electric fault in direct current systems. The device comprises an insulation monitoring device, wherein the insulation monitoring device comprises a processer, a bus connection interface, an axle type resistance control circuit, an adjustable resistance control circuit and a current transformer. The method includes the steps that according to the difference between the voltage to ground of the positive electrode of the first direct current system and the voltage to ground of the positive electrode of the second direct current system, and therefore whether the loop channeling electric fault exists between the two direct current systems or not is judged; when the loop channeling electric fault exists between the two direct current systems, an adjustable resistor is connected in according to the voltages to ground of the positive electrodes and the negative electrodes of the direct current systems, and the resistance value of the adjustable resistor is adjusted; current data acquisition is conducted on the current transformer connected to a feeder wire, and the feeder wire where the loop channeling electric fault occurs is positioned according to the preset change rules and the change rules of the obtained current data. By means of the device and method, the loop channeling electric fault can be found and positioned rapidly, accurately and safely. The device and method can be widely applied to the field of electric systems.