Background
Thermal resistors are the most widely used thermometers in industry, and their resistance value varies with the temperature of the contact medium. Response time is an important performance index of a thermal resistor, and is defined as the time required for the resistance value of the thermal resistor to change to 63.2% of a step change when the temperature of a medium in which the thermal resistor is located changes in a step change.
The traditional thermal resistance response time test is generally completed in a laboratory by adopting an insertion method, which needs to remove the thermal resistance from a process environment, and cannot reflect the influence of transportation, installation, use condition difference and the like of the thermal resistance in the use process, such as the clearance between a thermometer element and a sleeve, impurities and the like. In some domestic nuclear power plants, in-situ measurement has been required to periodically test the response time of the thermal resistor.
The response time of the thermal resistor is measured in situ by a loop current step response method. The loop current step method adds a step current of a plurality of milliamperes to a lead of the thermal resistor to cause self-heating of the resistor element, a resistance value transient change signal caused by the self-heating of the thermal resistor is measured, and the response time of the thermometer is given through model calculation.
Therefore, a multi-channel thermal resistor in-situ response time testing device is particularly needed to solve the existing problems.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a multichannel thermal resistance normal position response time testing arrangement, to the not enough of prior art, the automatic test of multichannel has reduced on-the-spot test time, has reduced manual operation work load, has reduced the people because of the mistake, has improved measurement accuracy.
The utility model provides a technical problem can adopt following technical scheme to realize:
a multi-channel thermal resistor in-situ response time testing device is characterized by comprising a signal acquisition device and a portable mobile terminal, wherein the signal acquisition device is in communication connection with the portable mobile terminal; the signal acquisition device comprises a programmable power supply, a signal acquisition unit and a plurality of measurement bridges, wherein the measurement ends of the measurement bridges are respectively connected with thermal resistors, the output ends of the measurement bridges are connected with the signal acquisition unit, and the input ends of the measurement bridges are connected with the programmable power supply.
In an embodiment of the present invention, the measuring bridge is composed of a resistor R1, a resistor R2, an adjustable resistor R3, an adjustable resistor R4 and a switch K1, one end of the resistor R1 is connected to one end of a resistor R2 and to one end of a programmable power supply, the other end of the resistor R2 is connected to one end of the adjustable resistor R4 and to one end of a signal acquisition unit and one end of a thermal resistor, the other end of the resistor R1 is connected to one end of the adjustable resistor R3 and to the other end of the signal acquisition unit, the other end of the adjustable resistor R4 is connected to pin 1 of the switch K1, the other end of the adjustable resistor R3 is connected to a control end of the switch K1 and to the other end of the programmable power supply, and pin 2 of the switch K1 is connected to the other end of the thermal resistor.
Further, the switch K1 is a programmable selection switch.
In an embodiment of the present invention, the signal collecting device and the portable mobile terminal are connected to each other through wired or wireless communication.
Compared with the prior art, the multichannel thermal resistor in-situ response time testing device has the function of automatic acquisition, and can automatically complete data acquisition according to the set acquisition times; the measurement precision is improved, and the influence of the temperature drift of the bridge circuit resistance on the measurement is minimized; the simultaneous measurement of multiple channels is supported, and the field measurement time is reduced; the step current limit value is set and the maximum protection current is set, thus realizing the purpose of the utility model.
The features of the present invention will be apparent from the accompanying drawings and from the detailed description of the preferred embodiments which follows.
Detailed Description
In order to make the technical means, creation features, achievement purposes and functions of the present invention easy to understand and understand, the present invention is further explained by combining with the specific drawings.
Examples
As shown in fig. 1, the multi-channel thermal resistor in-situ response time testing device of the present invention includes a signal acquisition device 10 and a portable mobile terminal 20, wherein the signal acquisition device 10 and the portable mobile terminal 20 are in communication connection with each other; the signal acquisition device 10 comprises a programmable power supply 11, a signal acquisition unit 12 and a plurality of measurement bridges 13, wherein the measurement ends of the measurement bridges 13 are respectively connected with the thermal resistors 30, the output end of the measurement bridge 13 is connected with the signal acquisition unit 12, and the input end of the measurement bridge 13 is connected with the programmable power supply 11.
The number of the measurement bridges 13 can be adjusted according to requirements, the programmable power supply 11 can control output voltage by using the portable mobile terminal 20, and the signal acquisition unit 12 can simultaneously acquire voltage outputs of all the measurement bridges 13 and can adjust the range of the acquired voltage to improve measurement accuracy. The signal acquisition unit 12 has an overpressure protection function.
In this embodiment, the measurement bridge circuit 13 is composed of a resistor R1, a resistor R2, an adjustable resistor R3, an adjustable resistor R4 and a switch K1, one end of the resistor R1 is connected with one end of the resistor R2 and is connected with one end of the programmable power supply 11, the other end of the resistor R2 is connected with one end of the adjustable resistor R4 and is connected with one end of the signal acquisition unit 12 and one end of the thermal resistor 30, the other end of the resistor R1 is connected with one end of the adjustable resistor R3 and is connected with the other end of the signal acquisition unit 12, the other end of the adjustable resistor R4 is connected with pin 1 of the switch K1, the other end of the adjustable resistor R3 is connected with a control end of the switch K1 and is connected with the other end of the programmable power supply 11, and pin 2 of the switch K1 is connected with the other end.
Further, the switch K1 is a programmable selection switch.
The measurement bridge 13 can minimize the influence of the bridge resistance drift on the measurement, and the switch K1 is a programmable selection switch and can be controlled by the portable mobile terminal 20; the adjustable resistor R3 and the adjustable resistor R4 can be adjusted through the signal acquisition device 10, and the resistance values of the resistor R1 and the resistor R2 are equal.
In the present embodiment, the signal acquisition device 10 and the portable mobile terminal 20 are connected to each other in a wired or wireless manner.
When in measurement, a small voltage is applied to the measurement bridge circuit 13, and the balance of the measurement bridge circuit 13 is adjusted; then, a large voltage is applied to the measurement bridge circuit 13, and if the resistance values of the other resistors on the measurement bridge circuit 13 are not changed, the resistance value (temperature) change curve of the thermal resistor 30 can be obtained by collecting the voltage curve output by the measurement bridge circuit 13, so that the other resistors on the measurement bridge circuit 13 can be in a large current state for a long time, and only the current flowing through the resistors generates a step change.
The data collected by the signal collection device 10 can be automatically collected, displayed, stored and processed at the portable mobile terminal 20. The portable mobile terminal 20 can control the voltage output by the programmable power supply 11 and the selection switch K1 to realize automatic data acquisition, and can set the maximum current applied to the thermal resistor 30 to protect the on-site thermal resistor 30 from being damaged.
The utility model discloses a multichannel thermal resistance normal position response time testing arrangement's concrete measurement step as follows:
1) connected to an in situ thermal resistor 30;
2) controlling the programmable power supply 11 to output a smaller voltage;
3) the switch K1 is set in position 2 and the adjustable resistor R3 is adjusted so that the measurement bridge 13 is balanced, i.e. the resistance RX of the thermal resistor 30 is R3;
4) the switch K1 is set to position 1 and the adjustable resistor R4 is adjusted to balance the measurement bridge 13, i.e. R3 — R4;
5) controlling the programmable power supply 11 to output a larger voltage, waiting for a period of time, and measuring the small change of the resistance value of each resistance element of the bridge circuit 13 due to the self-heating effect;
6) the switch K1 is arranged at the position 2, the thermal resistor is heated by current, the output voltage of the measuring bridge circuit 13 changes, and the change process of the output voltage of the measuring bridge circuit 13 is collected by the portable mobile terminal 20 and is counted as a data collection process;
7) after a period of time, placing the switch K1 in the position 1, waiting for a period of time, and waiting for the thermal resistor to cool;
8) and (6) repeating the steps (6) and (7) until the data acquisition times reach a preset value.
The basic principles and the main features of the invention and the advantages of the invention have been shown and described above. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are intended to illustrate the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined by the appended claims and their equivalents.