JPH01291622A - Protective system for machinery - Google Patents

Abstract

PURPOSE:To serve a power conduction control signal line as an overload detection line by connecting the contact in an overload detector in series with the coil in a power conduction control relay. CONSTITUTION:An outdoor unit 1 comprises a compressor 3 and an outdoor fan 4. The compressor 3 has a temperature detector 5 and the contact thereof is connected with the exciting winding of a relay 7. The relay 7 switches power conduction to the compressor 3 through a contact 8. Upon opening of the contact 5 in the temperature detector, power supply to the compressor 3 is interrupted through the relay 7. power supply to the relay 7 is controlled based on an output from the inverter 11 in an indoor unit 2. Actual power supply to the relay 7 is judged based on comparison of voltage to be applied onto the exciting winding of the relay 7 through a comparator 13. If the relay 7 is not excited when a power supply command is fed from the inverter 11, a microcomputer 12 judges overload of the compressor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to protection of equipment or protection of a system including equipment when an overload condition occurs in the equipment.

(b) Conventional technology In general, the conventional protection method for equipment is
There was something like the one described in the publication. The system described in this bulletin detects the temperature of the electric motor (equivalent to equipment) with a temperature-sensitive switch, and when the temperature of the motor rises, the contacts of the temperature-sensitive switch are opened to cut off the power to the motor and cause the electric motor to start running. It was designed to protect against overheating.

(c) Problems to be Solved by the Invention In the device protection system configured as described above, if an abnormality (such as an overload condition) occurs while the motor is operating and the temperature inside the motor rises, the The contact piece of the temperature switch opened and stopped the power supply to the motor, but in the conventional technology, the motor and the detection signal generator that indicates the abnormal state are in the same unit. Generally, motor operation control is performed within the same unit, and when motor operation control is performed from different units, the signal lines for detection signals are separated according to the power connection circuit. There was a need. For this reason, the number of control lines and signal lines to be separated increases depending on the number of devices to be controlled (such as electric motors), leading to problems such as wiring errors and complicated distribution processing.

In view of such problems, the present invention provides a system that allows a device and a control section of the device to be controlled without adding control lines or signal lines.

(d) Means for Solving the Problems The present invention provides a system for energizing the equipment by opening and closing contacts of a relay, and controlling energization to the excitation winding of the relay by a control section separate from the equipment. In the protection method, a contact piece of an overload detection section that opens when detecting an overload state of the device is connected in series with the excitation winding of the relay, and detects whether the excitation winding of the relay is energized or de-energized. An energization detection section is provided in the control section, and the opening/closing of the contacts of the overload detection section is determined based on the output of the energization detection section, thereby performing a protective operation for the device or the system.

(*) Effect In the device protection system configured in this way, when an abnormal condition such as an overload occurs in the device, the contact of the overload detection section opens and stops the power supply to the device, and at the same time, the relay is energized. The current supply circuit to the winding is cut off, the operation of the overload detection section is transmitted to the control section, and the control section performs a protective operation in response to this operation.

Embodiments Below, embodiments of the present invention will be described based on the drawings. FIG. 1 is a schematic electrical circuit diagram in which the embodiment is used in a separate air conditioner consisting of an outdoor unit 1 and an indoor unit 2. The outdoor unit 1 has a compressor 3 and an outdoor blower 4. Compressed Ja3 is placed inside or on the outer wall of the case.
It has a temperature detector 5 that opens the contact piece at a predetermined temperature or higher, and a current detector 6 that opens the contact piece at a predetermined current or higher. The contact piece of the current detector 6 is connected in series with the winding of the motor section of the compressor @ 3, and when an overcurrent flows through the winding, this contact piece opens and directly cuts off the current to the compressor 1. . The contact piece of the temperature detector 5 is connected in series with the excitation winding of the relay 7, and cuts off the power to the excitation winding of the relay 7 when the temperature inside the compressor 3 or the case becomes high. 8 is a normally open contact piece of the relay 7, which controls the supply of electricity to the compressor 3. In addition, outdoor blower 4
may be linked to 0N10FF of the compressor 3, or a separate relay may be provided so that the operation can be controlled by the output from the indoor unit 2.

The indoor unit 2 and the outdoor unit 1 are connected to a signal line 1. which controls the energization of the relay 7. ,! 1. In indoor unit 2, signal line 1. is connected to the DC power supply +Vcc. The signal line P is connected to the output terminal of the inverter circuit 11 via diodes 9 and 10 in series.

An H level voltage or an L level voltage from a terminal OL of a main control microcomputer 12 is applied to this inverter circuit 11 .

When an H level voltage is applied, the output of the inverter circuit 11 becomes an L level voltage, and the excitation winding of the relay 7 is energized.6 (When the contact piece of the temperature detector 5 is closed) Terminal 01 of the microcomputer 12 When is an L level voltage, the output of the inverter circuit 11 is an H level voltage (Habo+V e cTM,
voltage), and the current supply to the excitation winding of the relay 7 is cut off. 13 is a comparator whose inverting input terminal is connected to the anode side of the diode 9, and its non-inverting input terminal is connected to the resistor 14.15.
It is reading directly from the constant potential divided by . This constant potential is approximately 1
(V), so when the output of the impark circuit 11 is an L level voltage, current flows through the diodes 9 and 10 and a voltage drop (approximately 1.5 to 2.0 O) occurs, so this voltage is compared. The blurring output applied to the inverting input terminal of the device 13 becomes an L level voltage. Also, the output of the inverter circuit 11 is H
At the level voltage, no current flows through the diodes 9 and 10 and no voltage drop occurs, so the output of the comparator 13 becomes an H level voltage. That is, the output of the comparator 13 is an L level voltage when the excitation winding of the relay 7 is energized, and is an H level voltage when the excitation winding of the relay 7 is not energized.

16 is an AND gate, which takes the logical product of the output of the comparator 13 and the terminal 01 of the microcomputer 12, and outputs the result to the terminal I of the microcomputer 12.

Therefore, the output of the AND gate 16 becomes an H level voltage only when the output of the terminal 0□ of the microcomputer 12 is an H level voltage and the excitation winding of the relay 7 is not energized. When the H level voltage is applied to terminal I, the microcomputer 12 determines that there is an abnormality due to the operation (opening of the contact piece) of the temperature detector 5 installed in the compressor 3 of the outdoor unit 1, and starts air conditioning. Stops the machine and displays an abnormal condition.

In addition, 17 is an indoor fan whose operation is controlled by the microcomputer 12, 18 is a setting unit that provides setting values such as room temperature, selection of cooling/heating, humidity, and wind speed to the microcomputer 12, and 19 is an environment control unit that provides environment settings such as temperature and humidity to the microcomputer 12. This is an environment detection unit that provides measured values.

FIG. 2 is an electrical circuit diagram showing a main part of another embodiment of the outdoor unit 1 shown in FIG. 1. The difference from the outdoor unit 1 shown in FIG. The point is that what is connected is not the contact piece of the temperature sensor 5 but the contact piece of the current detector 6.

The contact piece of the temperature detector 5 is connected in series with the winding of the motor section of the compressor 3, and when the temperature of the compressor 3 becomes high, the contact piece is opened to provide temperature protection.

Furthermore, when an overcurrent flows through the windings of the motor section of the compressor 3, the contacts of the current detector 6 open, and the microcomputer 12 determines whether there is an abnormality due to this operation. Therefore, the microcomputer 12 protects against overcurrent, for example, stops the compressor 3 for three minutes.

This protection is provided when the current value at which the contact piece of the current detector 6 opens is set to the current value Nt that flows when the pressure difference between high and low pressures in the refrigeration cycle is large and the compressor 3 does not start. If the pressure difference between high and low pressures within the cycle becomes small, normal startup can be performed. Furthermore, when the current value is set to a current value that flows during overload (larger than the current value), the microcomputer 12 stops the operation of the air conditioner.

FIG. 3 is a main part electric circuit diagram showing still another embodiment of the outdoor unit 1 shown in FIG. 1. The difference from the outdoor unit 1 shown in FIG. The point is that what is connected to is not the contact piece of the temperature sensor 5 or the contact piece of the current detector 6, but the contact piece of the pressure sensor 20. still,
The contact piece of the temperature sensor 5 and the contact piece of the current detector 6 are connected to the compressor 3.
is connected in series with the winding of the motor section. The pressure detection unit 20 is installed at a position where it can detect the pressure on the high pressure side in the refrigeration cycle (compressor discharge pressure), and when the high pressure exceeds the set pressure, it opens the contact piece and controls its operation using a microcomputer. Let 12 decide. The microcomputer 12 determines this operation and stops the operation of the air conditioner.

In addition, in Fig. 1, the energization detection section is a diode 9.10.
are connected in series and the voltage drop during energization is used, but this voltage drop can also be detected by using resistors instead of the diodes 9 and 10.

Furthermore, when the relay 7 is an AC relay, a COT (current transformer) may be used.

With this complete protection system, by selecting the contacts of the overload detection section that are connected in series with the excitation winding of the relay, the control section can determine various overload conditions. Appropriate protective operations can be performed based on the type of load condition.

(G) Effects of the Invention The present invention provides a protection system for equipment in a system in which the equipment is energized by opening and closing relay contacts, and the energization to the excitation winding of the relay is controlled by a control unit separated from the equipment. A contact piece of an overload detection section that is connected in series with the excitation winding of the relay and opens upon detecting an overload state of the device; The device uses an energization detection section that detects the energization state, and performs protective operations for the equipment or system by determining whether the contacts of the overload detection section are open or closed based on the output of the energization detection section, so that it is possible to prevent the equipment from being overloaded. When an overload condition occurs, it can be determined whether the relay is energized or not, and there is no need to provide a special signal line for overload detection, which simplifies the wiring of the system including equipment and eliminates errors. Wiring can be reduced.

[Brief explanation of the drawing]

Fig. 1 is an electrical circuit diagram of the main parts when the embodiment of the present invention is used in an air conditioner, and Fig. 2 is an electrical circuit diagram of the main parts showing another embodiment of the outdoor unit shown in Fig. 1. FIG. 3 is a main part electric circuit diagram showing still another embodiment of the outdoor unit shown in FIG. 1. 1...Outdoor unit, 2...Indoor unit,
3...Compressor, 5...Temperature detector, 6...
Current detector, 7... Relay, 8... Contact piece,
9, 10...Diode, 12...Microcomputer.

Claims (1)

[Claims] (1) In a protection method for the equipment of a system in which the equipment is energized by opening and closing relay contacts, and the energization to the excitation winding of the relay is controlled by a control unit separated from the equipment, the excitation winding of the relay A contact piece of an overload detection section that is connected in series and opens when detecting an overload state of the device, and a contact piece of an overload detection section that is provided in the control section and that is energized to detect the energized state or non-energized state of the excitation winding of the relay. 1. A protection method for equipment, characterized in that a detection unit is used to determine whether a contact piece of an overload detection unit is open or closed based on an output of the energization detection unit, and a protective operation is performed for the equipment or the system.