CN105590444A - Device for patrol detection of power line transmission temperature - Google Patents

Abstract

The invention relates to a device for patrol detection of power line transmission temperature. The device adopts a frequency modulation (FM) mode, a temperature signal is transmitted by an alternating-current 220V power line, three temperature detection channels adopting the carrier frequencies of 170 kHz, 200 kHz and 230 kHz respectively are arranged, the temperatures of three different sites of a detected system can be monitored, and once the temperature of a certain site exceeds the prescribed temperature limit, an alarm signal is sent out, and the specific position of the site where the temperature exceeds the limit is indicated. The device includes a transmitting circuit and a receiving circuit. The temperature control range of the device is 0-100 DEG C, the temperature control precision is +/-1 DEG C, and the furthest transmission distance is 1000 m.

Description

Device for roving detection of power line transmission temperature

technical field

The device adopts frequency modulation FM mode, and the temperature signal is transmitted through the AC 220V power line. There are three temperature detection channels with carrier frequencies of 170kHz, 200kHz, and 230kHz, which can monitor the temperature of three different locations of the system under test. Monitoring, once the temperature at a certain point exceeds the specified temperature limit, an alarm signal will be issued and the specific location of the over-temperature point will be indicated. The temperature control range of the device is 0°C~100°C, the temperature control accuracy is ±1°C, and the transmission distance is up to 1000m.

Background technique

If the temperature is too high during power line transmission, it will bring potential safety hazards. If it is not found and dealt with in time, it may cause a fire accident and cause personal injury and property loss. Detecting the temperature transmitted by the power line can predict danger, and take appropriate measures in time to eliminate potential safety hazards. Therefore, it is very important to detect the transmission temperature of the power line.

Contents of the invention

The device for itinerantly detecting the temperature transmitted by the power line is characterized in that the device is divided into two parts: transmitting and receiving circuits; the transmitting part circuit is mainly composed of a T/F temperature detection circuit, an analog switch sampling circuit, a roving counting circuit, and a power line carrier modulation circuit; The temperature detection circuit uses a 555 circuit for temperature-frequency conversion, and the relationship between circuit temperature and frequency is ; The analog switch sampling circuit samples the three-way temperature signal by connecting different analog switches respectively; the frequency modulation and transmitting circuit takes the audio phase-locked loop integrated circuit LM567 as the core, plus some components and the analog switch IC6; the receiving part is mainly composed of Receiving, amplifying, demodulating, shaping, frequency comparison, relay output and other circuits; receiving and amplifying circuit is composed of six NOT gate circuit IC1 and coupling transformer T1; demodulating circuit is composed of LM567, analog switch, decimal calculator, oscillator, etc. Composition; Shaping, frequency comparison and relay output circuit is composed of NOT gate circuit IC4, frequency comparison circuit IC6, and relay output circuit.

The device for itinerantly detecting the transmission temperature of a power line is characterized in that: the temperature control range of the device is 0°C to 100°C, the temperature control accuracy is ±1°C, and the maximum transmission distance is 1000m.

The device for itinerantly detecting the temperature transmitted by the power line is characterized in that: the temperature sensing head is a precision thermistor of MF58 type, wherein the resistance value at room temperature is R=5kΩ.

The device for roving detection of power line transmission temperature is characterized in that: IC1, IC2, and IC3 in the transmitting part circuit use 555 chips, decimal counter IC4 uses CD4017 chips, analog switches IC5 and IC6 use CD4066 chips, and audio phase-locked loops are integrated The circuit IC7 uses the LM567 chip, the inverter IC8 uses the CD4069 chip, and the regulator IC9 uses the LM7809 chip.

The device for roving detection of power line transmission temperature is characterized in that: the inverter IC1 in the receiving part circuit uses a CD4069 chip, the audio phase-locked loop integrated circuit IC2 uses an LM567 chip, the decimal counter IC3 uses a CD4017 chip, and the inverter IC4 uses a chip CD4069 chip, analog switch IC5 uses CD4066 chip, audio phase-locked loop integrated circuit IC6 uses LM567 chip, voltage regulator IC7 uses LM7809 chip.

The device for itinerant detection of power line transmission temperature is characterized in that: the transistors VT1 and VT2 of the transmitting part of the circuit are NPN transistors; the transistors VT1 and VT2 of the receiving part of the circuit are NPN transistors, VT3 is a PNP transistor, and VT4 is an NPN transistor.

The device adopts frequency modulation FM mode, and the temperature signal is transmitted through the AC 220V power line. There are three temperature detection channels with carrier frequencies of 170kHz, 200kHz, and 230kHz, which can monitor the temperature of three different locations of the system under test. Monitoring, once the temperature at a certain point exceeds the specified temperature limit, an alarm signal will be issued and the specific location of the over-temperature point will be indicated. The device is divided into two parts: transmitting and receiving circuits.

(1) The circuit of the transmitting part

The schematic diagram of the transmitting part of the circuit is shown in Figure 1. It is mainly composed of a T/F temperature detection circuit, an analog switch sampling circuit, a circuit counting circuit, and a power line carrier modulation circuit.

1. Temperature detection circuit

The signal transmitted by the telemetry system is a digital quantity, so the temperature signal needs to be converted into a frequency signal. The device uses a 555 circuit for temperature-frequency conversion, and the relationship between circuit temperature and frequency is

Substituting the resistance value of the thermistor at different temperatures into the formula, the specific data between temperature and frequency can be obtained.

2. Analog switch sampling circuit

The IC5 analog switch circuit samples the three-way temperature signal by switching on different analog switches respectively. The control signal of the itinerant sampling is provided by pins Q1, Q2, and Q3 of the decade counter IC4. The 12 pins of the carry terminal of IC4 are connected with the 15 pins of the reset terminal to form a decimal cycle counter. The CP terminal of IC4 is the counting pulse input terminal. For one pulse, the circuit counts once. The counting pulse at the CP end is provided by the six NOT gate circuit IC8, and IC8 constitutes a multivibrator. The period T of the oscillator can be calculated according to the parameters in the figure seconds, that is, a counting pulse is generated every 3 seconds, and the time for each Qn terminal of the decade counter IC4 to output a high level is about 3 seconds, and one of the temperature signals is sampled within 3 seconds, and the time for sampling once The interval is about 30 seconds.

3. Frequency modulation and transmitting circuit

This circuit is composed of audio phase-locked loop integrated circuit LM567 as the core, plus some components and analog switch IC6. The temperature-frequency signal converted by the 555 circuit is sent to the 2-pin of the 567 by R7 and C7 after the analog switch, and the FM signal is output from the 5-pin. The high-frequency carrier output by pin 5 is set by analog switches IC6A, B, and C, which can be set to three frequencies of 170kHz, 200kHz, and 230kHz respectively, thus forming three temperature detection channels. After the FM signal is amplified by VT1 and VT2, it is coupled to the power line through transformer T2, inductors L1, L2, and capacitors C14 and C15.

(2) Receive part of the circuit

The receiving part is mainly composed of receiving, amplifying, demodulating, shaping, frequency comparison, relay output and other circuits. Figure 2 is a schematic diagram of the receiving part of the circuit.

1. Receiving and amplifying circuit

It is composed of six NOT gate circuit IC1 and coupling transformer T1. The FM signal sent from the power line is added to pins 5 and 6 of T1 through C16, C17, L1 and L2, and then output through both ends of transformer 1 and 2, and then passed through After VD1 and VD2 are limited, they are added to a three-stage linear amplifier circuit composed of a non-gate circuit IC1 for amplification.

2. Demodulation circuit

The circuit is composed of LM567, analog switch, decimal calculator, oscillator and so on. After the FM signal on the power line is amplified, it enters the audio phase-locked loop demodulation circuit IC2 through C6 and R8. The center frequency of the internal voltage-controlled oscillator of the phase-locked loop depends on the external resistance R and capacitance C of pins 5 and 6, and the calculation formula is

The PLL can capture the maximum bandwidth of the signal , Only the FM signal falling within this bandwidth can be demodulated by the internal demodulation circuit, and the audio signal is output from pin 1, at this time, pin 8 outputs low level.

The analog switches IC5A, B, and C are used to select the center frequency of the voltage-controlled oscillator inside the audio phase-locked loop IC2 circuit. There are 3 types of settings, the frequencies are 170kHz, 200kHz, and 230kHz, which correspond to the three temperature detection channels of the transmitting part respectively. Use IC2 to demodulate the temperature signals in different channels.

The control signal of the analog switch is provided by the decade counter IC3. In this circuit, the Q3 terminal of IC3 is directly connected to the reset terminal 15 to form a quaternary counter, and the counting pulse is supplied by the oscillator circuit composed of IC1E and F, the frequency of the oscillator circuit is determined by R17 and C8, and the oscillation is calculated according to the parameters in the figure Period T=1 second. That is to say, the time for Q0, Q1, and Q2 to be at high level is 1 second, and the cycle time is about 3 seconds. Within this 3 seconds, the three temperature detection channels are cyclically sampled once. Once a certain The FM signal of the channel is assumed to be channel 2, that is, after the signal with a frequency of 200kHz is captured by the 567, pin 8 of the 567 outputs a low level, and the resistor R19 makes VT1 cut off, VT2 is turned on, and the carry pulse input terminal CP is pulled to On the low level, when the FM signal of channel 2 is valid, the analog switch IC5B is always on, and the A and C switches are in the off state, keeping automatic tracking of the FM signal of channel 2. Since the effective time of any FM signal of the three temperature channels transmitted from the power line is about 3 seconds, a certain FM signal of the three temperature channels can always be captured within 3 seconds.

3. Shaping, frequency comparison and relay output circuit

The temperature-frequency signal demodulated by IC2 is output from pin 1, amplified by the non-gate circuit IC4A, and then sent to the frequency comparison circuit IC6 after two-stage shaping of B and C.

IC6 is the external potentiometer RP4 and capacitor C11 of the 5 and 6 pins of the audio phase-locked loop integrated circuit LM567, which determine the center frequency f1 of the internal voltage-controlled oscillator of the integrated block. Because in the transmitting circuit, the output frequency of the 555 circuit and the temperature One-to-one correspondence, you can choose a certain temperature between 0°C and 100°C as the alarm point, and there is a corresponding alarm frequency corresponding to this point, which can be set by the potentiometer between pins 5 and 6 of IC6 in the receiving circuit Frequency f1, if the temperature-frequency signal input by IC6 is consistent with the set alarm frequency f1, then pin 8 of IC6 outputs a low level, and VT3 is turned on through R23, VT4 is turned on, and the relay is energized to work. The contact J1-2 is closed to make the relay self-lock, the contact J1-1 is closed to make VT1 cut off, and VT2 is turned on, so that one of Q0, Q1, and Q2 of IC3 keeps high level, and the temperature signal of the corresponding channel has been turned on. The preset temperature limit has been exceeded.

Description of drawings

The schematic diagram of the transmitting part of the device in Fig. 1.

Figure 2 is a schematic diagram of the receiving part of the circuit.

detailed description

1. Transmitting circuit. Adjust the potentiometers RP1, RP2, and RP3 respectively so that the carrier frequency of the audio phase-locked loop IC7 is 170kHz, 200KHz, and 230kHz. The temperature sensor head uses MF58 precision thermistor, and the resistance value at room temperature is R=5kΩ.

2. Receive circuit. Connect the signal generator to the 5 and 6 ends of the coupling transformer T1, so that the high-frequency signals output by the signal generator are 170kHz, 200kHz and 230kHz respectively. At this time, adjust the potentiometers RP1, RP2 and RP3 respectively to make the audio phase-locked loop Pin 8 of IC2 outputs low level. In order to accurately control the temperature, the actual value of potentiometer RP4 and capacitor C11 should be carefully adjusted. Since the external frequency that the phase-locked loop 567 can capture has a minimum frequency and a maximum frequency, which are designed as fmin and fmax respectively, when designing the alarm temperature, the corresponding alarm frequency should be based on fmin, and set the value of fmin by adjusting the potentiometer RP4 value.

Claims (6)

1. the device of touring detection power line transmission temperature, is characterized in that this device divides transmitting and receives two large divisions's circuit;Radiating portion main circuit will be adjusted by T/F temperature sensing circuit, analog switch sample circuit, touring counting circuit, power line carrierThe compositions such as circuit processed; Temperature sensing circuit adopts 555 circuit to do temperature-frequency transformation, and the pass between circuit temperature-frequency is; Analog switch sample circuit is touring by connecting respectively different analog switch Dui San road temperature signalsSampling; Frequency modulation(PFM), radiating circuit be taking audio pll ic LM567 as core, more additional elements and analog switchIC6 forms; Receiving unit mainly by reception, amplification, demodulation, shaping, frequency ratio, the electric circuit constitutes such as relay output; Receive,Amplifying circuit is made up of six not circuit IC1 and coupling transformer T1; Demodulator circuit is by LM567, analog switch, decimal computationThe formation such as device, oscillator; Shaping, frequency ratio and outputting circuit for relay by not circuit IC4, frequency comparison circuit IC6, continueElectrical equipment output circuit forms.

2. the device of touring detection power line transmission temperature according to claim 1, is characterized in that: the temperature control of this deviceScope is 0 DEG C ~ 100 DEG C, and temperature-controlled precision is ± 1 DEG C, and transmission range is 1000m farthest.

3. the device of touring detection power line transmission temperature according to claim 1, is characterized in that: Temperature probe choosingWith MF58 type accurate thermistor, wherein normal temperature resistance value R=5k Ω.

4. the device of touring detection power line transmission temperature according to claim 1, is characterized in that: radiating portion circuitMiddle IC1,, IC2, IC3 use 555 chips, decade counter IC4 uses CD4017 chip, analog switch IC5, IC6 useCD4066 chip, audio pll ic IC7 uses LM567 chip, and inverter ic 8 uses CD4069 chip, voltage-stablizerIC9 uses LM7809 chip.

5. the device of touring detection power line transmission temperature according to claim 1, is characterized in that: receiving unit circuitMiddle inverter ic 1 uses CD4069 chip, and audio pll ic IC2 uses LM567 chip, decade counter IC3Use CD4017 chip, inverter ic 4 uses CD4069 chip, and analog switch IC5 uses CD4066 chip, audio phase locking ring collectionBecome IC circuit 6 to use LM567 chip, voltage-stablizer IC7 uses LM7809 chip.

6. the device of touring detection power line transmission temperature according to claim 1, is characterized in that: radiating portion circuitTriode VT1, VT2 are NPN triode; Receiving unit circuit triode VT1, VT2 are NPN triode, and VT3 is PNP triode,VT4 is NPN triode.