JP2674261B2 - Automatic power factor controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a current control type automatic power factor control device.

2. Description of the Related Art A conventional automatic power factor control device of this type has a circuit configuration as shown in FIG. That is, in the figure, 1 is a current transformer connected to a load circuit, 2 is a current relay for detecting the output current of the current transformer 1, and 3 is a switching relay controlled by a current relay 2 inserted in a power supply circuit of a capacitor 4. The electromagnetic contactors 5 are wiring breakers inserted in a common power supply circuit for the current relay 2 and the capacitor 4. The operation is such that the current displacement from the current transformer 1 is detected by the current relay 2, the electromagnetic contactor 3 is opened and closed, and the capacitor 4 is put into the circuit and opened. That is, the capacitor 4 can be automatically turned on and off depending on the load variation.

In this conventional control device, as shown in FIG. 2, the current detection method in the automatic power factor control is such that the current transformer 1 is connected to the load side from the connection point of the capacitor 4 to the load circuit. It is a system in which only the current is detected and the capacitor 4 is opened and closed. In this way, only the load current is detected, when the combined current of the load current and the capacitor current is detected, the combined current is reduced by turning on the capacitor 4,
This is because the capacitor 4 causes a hunting operation depending on the setting of the current relay.

However, in such a circuit, three-phase (R
Phase, S phase, T phase), insert the connection terminal of each phase in the load circuit, and connect the circuit breaker 5 of the capacitor 4 to the load side of the connection terminal.
In some cases, a circuit breaker for load may be inserted in parallel with the above, and in this case, the current transformer 1 is installed at the relevant location for construction work (on the installation location).
In some cases it was impossible to install.

The present invention solves such a conventional problem, and provides an automatic power factor control device which surely exhibits a functional operation even if a current transformer is installed on the power supply side of a connection point of a capacitor to a load circuit. The purpose is to

Means for Solving the Problems In order to achieve the above object, the present invention provides a current control type automatic power factor control device, in which a current transformer is coupled to a load circuit on the power supply side from a connection point of the capacitor to the load circuit. The connection line from the load circuit to the capacitor is passed through the current transformer.

Action With the above configuration, the combined current of the load current and the capacitor current flows in the vector current in the direction opposite to the vector current flowing in the ammeter, and as a result, only the load current can be detected. It can perform various actions.

Embodiment An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the circuit connection is different from that of the conventional example shown in FIG. 2, so that the same parts as those in FIG.

That is, in the present invention, the current transformer 1 is coupled to the load circuit on the power supply side from the connection point of the capacitor 4 to the load circuit, and the connection line to the capacitor 4 is passed through the current transformer 1. is there.

Therefore, combined current in the figure Is = Il (load current) + Ic
(Capacitor current), the current of −Ic flows in vector due to the connection line to the capacitor 4 being passed through the current transformer 1, and as a result, Is = (Il + I
c) −Ic = Il will flow. That is, only the load current will flow. Other operations are the same as in the case of the conventional example shown in FIG.

EFFECTS OF THE INVENTION As is clear from the above embodiments, according to the present invention, even if the current transformer is installed on the power supply side with respect to the connection point of the capacitor, a reliable control operation can be performed, and thus the load side installation and There is no need to limit it, and the degree of freedom in installation increases.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of an automatic power factor control device according to an embodiment of the present invention, and FIG. 2 is an electric circuit diagram of a conventional automatic power factor control device. 1 ... Current transformer, 2 ... Current relay, 3 ... Electromagnetic contactor,
4 ... Capacitor.

Claims (1)

(57) [Claims] 1. An automatic power factor of a current control system in which a current transformer is coupled to a load circuit, an output current of the current transformer is detected by a current relay, and an electromagnetic contactor inserted in a power circuit of a capacitor is controlled. In the control device, the connection point of the current transformer to the load circuit is on the power supply side from the connection point of the capacitor to the load circuit, and the connection line from the load circuit to the capacitor is passed through the current transformer. Rate control device.