JPS6029154Y2 - DC auxiliary relay power supply circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power supply circuit that obtains driving power for a DC auxiliary relay from an AC power source using a transformer and a rectifier circuit.

A conventional circuit of this type has a configuration shown in FIG.

The secondary output of the transformer T, which is connected to the primary winding of the AC power source, is rectified by full-wave or half-wave rectification using a rectifier, and then connected to the resistor R and capacitor C.
DC voltage is taken out through the DC power supply, and the relay By is driven by turning on a switch SW between this DC power supply and the auxiliary relay Ry.

Here, the resistor R is used to reduce power consumption during driving of the relay by utilizing the difference between the operating voltage and the return voltage that DC relays generally have.

In other words, the operating voltage, which is about 70% of the rated voltage, is charged to the capacitor C before operation, and after operation, the operating voltage is about 1 of the rated voltage.
The current is suppressed by the voltage drop caused by the resistor R so that the operating state is maintained at a return voltage of about 0%.

However, when a plurality of relays Ry or a plurality of relays of different types are connected in parallel, it is necessary to change the capacitance of the capacitor C and the resistance R so as to obtain the necessary operating voltage period and holding current.

In addition, although the conventional circuit can reduce power consumption compared to the case where the resistor R is not provided, there is a problem that the resistor R consumes power, and if the holding current is large, the resistor R also needs to be large. there were.

In order to reduce the power consumption of the resistor R, it is conceivable to use a transistor or the like in place of the resistor R to operate as a chopper, but this requires a control circuit and has the problem of lower reliability due to an increase in the number of parts.

An object of the present invention is to provide a power supply circuit for a DC auxiliary relay that eliminates the above-mentioned problems.

FIG. 2 is a circuit diagram showing an embodiment of the present invention.

In the figure, a transformer T has two secondary windings N and ? N
2 is provided, one winding N□ is designed to output voltage that obtains the operating voltage required for the relay, and is configured to charge the capacitor C via the rectifier D and the resistor R, and the other winding N2 is designed to the output voltage that obtains the operating voltage required for the relay. The output voltage is designed to obtain the necessary holding voltage, and the capacitor C is charged through the rectifier D2.

According to this embodiment, the resistor R only needs to charge the capacitor C to the required voltage in a sufficiently long time from when the relay returns to the next operation when the switch S is opened, and its resistance value is set to a sufficiently large value. In terms of value, its power consumption and shape can be made sufficiently small.

After the relay R3/ is activated, the output voltage of the winding N2 is designed to supply the necessary holding current from the winding N2 side, so there is no need to insert a resistor between the winding N2 and the capacitor.
Eliminates extra power consumption during holding operations.

In addition, by designing the capacitance of the capacitor C in advance according to the expected number of connected relays in the same way as the setting of the resistor R, it is not necessary to change the constant of the resistor R together with the resistor R when changing the number of relays. Although the value is designed according to the number of connections, the power consumption in the resistor R can be made sufficiently low.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

This figure differs from FIG. 2 in that a tapped secondary winding N3 is used instead of the secondary winding N1.

This embodiment has a new effect of reducing the capacitance of the capacitor C compared to the case shown in FIG.

That is, since the winding N3 has multiple taps, when the number of relays is increased, some relays may not operate, which can be avoided by increasing the output voltage of the winding N3 by switching the taps. be able to.

FIG. 4 shows another embodiment of the present invention, and the difference between this figure and FIG. 2 is the primary winding N of the transformer T.

The point is that I used one with a tap.

In this embodiment, when the internal resistance of the winding N2 or the rectifier D2 is lower than the required output voltage due to the addition of a relay, the primary winding N is compared to that of FIG. 2 or 3.

The advantage is that the required holding current can be supplied by raising the tap.

Note that the present invention is not limited to the above embodiments, but
In the figure, the capacity of capacitor C is increased by adding a relay, in Figures 2 to 4, the rectifier is changed to a half-wave rectification circuit, and then a full-wave rectification circuit using a center-tapped transformer, and winding N1. A configuration in which a part of the winding N2 is shared, a configuration in which the insertion position of the resistor R is placed on the input side of the rectifier D1, a configuration in which a normally closed auxiliary contact of a part of the relay is provided in the circuit system of the winding N1, A configuration in which a tap is also provided on line N2,
In FIGS. 2 to 4, part of the windings N□ and N3 is the primary winding N.

A configuration that can be shared with other devices falls within the scope of this invention.

As described above, according to the present invention, it is possible to sufficiently increase the charging resistance of the capacitor up to the operating voltage required by the relay, thereby reducing its power consumption and downsizing the size, and by increasing or decreasing the number of relays. Sufficient current limitation can be achieved without replacing the capacitor.

Further, in terms of configuration, only a slight circuit change is required, such as changing the winding of the transformer and adding the rectifier D2.

[Brief explanation of drawings]

Figure 1 is a power supply circuit diagram of a conventional DC auxiliary relay, Figure 2~
FIG. 4 is a power supply circuit diagram showing an embodiment of the present invention. T: Transformer, Dl, D2: Rectifier, R: Current limiting resistor, C: Capacitor, Ry: Relay.

Claims (1)

[Scope of utility model registration request] The primary winding is connected to an AC power source, one secondary winding is connected to the AC power supply, one secondary winding is used to obtain the operating voltage required for the DC auxiliary relay, and the other secondary winding is connected to the AC auxiliary relay to obtain the holding voltage required for the DC auxiliary relay. a rectifier that rectifies the outputs of the secondary windings, and a capacitor connected in parallel to the DC auxiliary relay via a power supply switch, The output end of the rectifier connected to the other secondary winding is connected to the capacitor via a current limiting resistor, and the output end of the rectifier connected to the other secondary winding is directly connected to the capacitor. Relay power circuit.