JPS62160679A - Power controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power control device for an insulated heater.

2. Description of the Related Art A conventional on-off duty variable power control device for an insulated heater will be described with reference to FIGS. 5 and 6. Figure 5 is a circuit diagram. 1 is an insulated type heater in which the heater body is placed inside a pipe and filled with insulating material for safety, and a micro switch 3 is connected to both ends of an AC power source 2. thyristor 5CR1. 4 is an L-tension oscillator which generates a pseudo triangular wave as shown in FIG. 6(b). By comparing the waveform at point A and the potential at point B determined by the variable resistor VR, the duty ratio is determined by the comparator 6 of the duty ratio determination circuit 5, and the bidirectional thyristor 5CR1 is turned on and off. A signal is given to vary the heating amount of the heater 1. Furthermore, the microswitch 3 is mechanically linked to the variable resistor VR0, and when the power is reduced to zero, that is, in the "off" state, the contacts of the microswitch 3 are opened, and the bidirectional When the thyristor SCR is turned off, the heater 1 is isolated from the AC power source.

That is, from the "off" position of the variable resistor VR□.

When the duty ratio is set to an arbitrary position, the potential at point B becomes, for example, the potential shown by the broken line in FIG. 6(b).

When the potential at point A becomes higher than the potential at point B, the output of comparator 6 becomes low level, and bidirectional thyristor SC
Trigger R, and heater 1 is energized. Conversely, when the potential at point A becomes lower, the bidirectional thyristor 5CR1 is turned off and the heater 1 is not energized. The duty ratio of heater energization is determined by the ratio of the time during which the potential at point A is higher than the potential at point B and the entire time. Furthermore, when the variable resistor vR1 is set to the "off" position, it is insulated by the microswitch 3 and the bidirectional thyristor SCR, so safety is ensured even if the insulation of the heater 1 deteriorates. Note that FIG. 6(a) shows the on/off state of the microswitch 3, and FIG. 6(c) shows the on/off state of the bidirectional thyristor SCR.

Problems to be Solved by the Invention However, the conventional configuration described above requires the microswitch 3 and its additional mechanism, and the expensive bidirectional thyristor 5CR0 and its heat dissipation fins, making the device configuration complex and requiring a large space. Requires.

Means for Solving the Problems In order to solve the above problems, the power control device of the present invention includes:
A first relay having a first relay contact connected between one end of the insulated heater and the AC power source, and a second relay contact connected between the other end of the heater and the AC power source. a second relay having: a second relay that drives the first relay and then drives the second relay when energization starts, and stops driving the first relay and then drives the second relay when energization stops; a first relay sequential driving means for stopping the driving; and a first relay driving means for driving the second relay when starting energization, and then driving the first relay, and for driving the second relay when energizing is stopped.
a second relay sequential driving means that stops driving the first relay and then stops driving the first relay; an energization determining means that determines whether or not the heater is energized; The first and second relay sequential driving means are provided with an alternating driving means that alternately drives the first and second relay sequential driving means.

According to the above configuration, each cycle of energization to the heater:
1st relay on → 2nd relay on → 1st relay -
The first pattern is off → second glue layoff, and the second
Glue lay-on → 1st relay on → 2nd glue lay-off →
A second pattern called a first glue layoff is repeated alternately. Therefore, in the case of the first pattern, the second relay bears the wear of the contacts due to the arc when the contacts are on, and in the case of the second pattern, the first relay bears the burden, respectively.
Conversely, contact wear due to arcing when off is borne by the first relay in the case of the first pattern, and by the second relay in the case of the second pattern.
In the off cycle, contact wear due to arcing during on and off cycles can be divided into two relays. In addition, in the next cycle, by changing the distribution of contact consumption due to arcing during on/off, the life of the relay can be reduced by using half of the total on/off circuit6. In this case, the insulated heater can be easily isolated from the AC power supply by opening the two relay contacts, making it possible to realize an inexpensive, space-saving, and highly safe power control device.

EXAMPLE Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

FIG. 1 is a circuit block diagram of a power control device according to an embodiment of the present invention.
A first relay contact 12, an insulated heater 13, and a second relay contact 14 are connected in series to both ends of the relay 11. Reference numeral 15 denotes a first relay sequential driving means, which drives the first relay having the first relay contact 12 when the heater 13 starts being energized, and after a predetermined period of time drives the first relay having the first relay contact 12.
When the current supply is stopped, the first relay is stopped, and after a predetermined period of time, the relay of the cylinder 2 is stopped. 16 is a second relay sequential driving means;
At the start of energization, the second relay is driven, and then after a predetermined period of time, the relay of the cylinder 1 is driven, and when the energization is stopped, the second relay is stopped, and then the first relay is stopped. 17
Reference numeral 18 indicates an energization determining means for determining whether or not the heater 13 is energized; and 18, an energization determining means 15 that sequentially drives the first and second relays each time the energization determining means 17 outputs one cycle of output signals by turning on and off. .16 is an alternating drive means that alternately drives .16. With this configuration, it is possible to sequentially drive the first and second relay contacts 12, 14 in consideration of contact wear.

Figure 2 is a time chart of the circuit shown in Figure 1.

(a) shows the operation of the first relay contact 12, (b) shows the operation of the second relay contact 14, and (c) shows the output of the energization determining means 17.

That is, when the first relay sequential driving means 15 operates, a load is applied to the second relay contact 14 when the contact is on, and a load is applied to the first relay contact 12 when the contact is off, and conversely, the load is applied to the second relay contact 12 when the contact is turned off. When 16 is activated,
The burden of contact wear is placed on the first relay contact 12 when the contact is on, and on the second relay contact 14 when the contact is off.

By repeating this operation alternately by the alternate driving means 18, the first and second relay contacts 12.1
4, it becomes possible to use a device whose lifespan is half the number of openings and closings. Further, when the power is not energized, the insulated heater 13 can be easily completely insulated from the AC power source 11 by opening the first and second relay contacts 12.14. When the insulation of the heater 13 deteriorates.

If it is not completely insulated from the AC power source 11, the earth leakage breaker may trip or there may be a risk of electric shock.

In this embodiment, the duty control circuit has been described, but the same can be said even if the present invention is applied to a case where the energization decision is made by temperature control using a thermistor or the like.

FIG. 3 is a circuit diagram of a power control device according to an embodiment of the present invention. When the variable resistor VR is set to an arbitrary position, the voltage is converted into a digital signal by the A/D converter 19, and the voltage is converted to a digital signal by the A/D converter 19. 20 is input. The microcomputer 20 determines the energization/de-energization time according to this input signal, drives the transistors Q, , Q, and sequentially drives the coil 21 of the first relay and the coil 22 of the second relay. By doing so, the amount of heating to the heater 13 is variably controlled. 23 is a DC power supply, and R to R4 are resistors.

The operation of this sequential drive will be explained in detail using the flowchart of FIG. In step ■, the value N of the counter for alternating drive is set to O.In step ■, the presence or absence of the energization start signal to the heater 13 is determined.If the energization start signal is received, the value N of the counter is set to O in step 0, and if the counter value N is 0, step ■
energizes the coil 21 of the first relay to turn on the first relay contact 12, and after a predetermined time, energizes the coil 22 of the second relay to turn on the second relay contact 14 in step (3). . Next, in step (2), it is determined whether there is a energization stop signal for the heater 13, and if the energization stop signal is received, step (2)
In step (3), the energization to the coil 21 of the first relay is stopped and the first relay contact 12 is turned off, and after a predetermined time, in step (2), the energization to the coil 22 of the second relay is stopped and the first relay contact 12 is turned off. 2 relay contact 14 is turned off. Then, in step ■, one cycle of operation has been completed, so
Next, to perform the opposite operation, set the counter value N to 1. Next, return to step ■ and wait for the energization start signal of the heater 13 to arrive. 1 When the energization start signal comes, the counter value N is set to 1 in step Since the value N is 1, the operation of steps [phase] ~ @ (that is, the opposite operation of steps ■ ~ ■) is performed, and when the next energization start signal comes, the operation of steps ■ ~ ■ is performed this time. Repeat this action alternately.

In this way, when the heater 13 is not energized, it is possible to isolate it from the AC power source 11 by opening the first and second relay contacts 12.14 at both ends of the heater 13, and since it is sequentially turned on and off, First and second stray contacts 12.14
It is possible to bear the burden of consumption alternately.

Effects of the Invention As described above, according to the present invention, it is possible to produce a power control device that is inexpensive, space-saving, and ensures safety.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of a power control device according to an embodiment of the present invention, FIG. 2 is a timing chart of the circuit shown in FIG. 1, and FIG. 3 is a circuit diagram of a power control device according to an embodiment of the present invention. , FIG. 4 is a flowchart showing the operation of the circuit shown in FIG. 3, FIG. 5 is a circuit diagram of a conventional power control device,
FIG. 6 is a timing chart of the circuit shown in FIG. 11... AC power supply, 12... First relay contact, 1
3... Heater, 14... Second relay contact, 15.
...First relay sequential driving means, 16... Second relay sequential driving means, 17... Energization determining means, 18...
Alternate drive means agent Yoshi Morimoto Buddhist painting 1 Figure 11 - AC power supply Figure 2 Figure S Figure 3

Claims (1)

[Claims] 1. A first relay having a first relay contact connected between one end of the insulated heater and the AC power source, and a second relay connected between the other end of the heater and the AC power source. a second relay having a relay contact; when energization starts, the first relay is driven, and then the second relay is driven; when energization is stopped, the first relay is stopped, and then the second relay is driven; a first relay sequential driving means for driving and stopping the relays, and driving the second relay and then driving the first relay when starting energization, and stopping driving and then stopping the second relay when energization is stopped; a second relay sequential driving means for driving and stopping the first relay; an energization determining means for determining energization/de-energization of the heater; and a sequential driving of the first and second relays based on the output of the energization determining means. and alternating driving means for driving the means alternately.