JPH0676708A - Time limit relay - Google Patents

Abstract

PURPOSE:To provide a time limit relay capable of controlling an output signal even if failure occurs in a timer, in the time limit relay, integrated into a control circuit, and composed of the timers and contacts. CONSTITUTION:A time limit relay, consisting of timers and contacts, are composed of the timer 11 having a fixed time limit set value, and the timer 21 having a longer time limit set time than the time limit set time of the timer 11. In the case of the failure of the timer 11, its control is continued by the timer 21 so as to obtain an output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time relay which is used in a control circuit and a control device and can prevent a single unit failure.

[0002]

2. Description of the Related Art Conventionally, a time relay is composed of one timer and a contact interlocking with this timer.
That is, FIG. 3 is a block diagram of a time relay according to the prior art, in which 1 is a timer, 2 is a contact of the timer 1, and X is an input signal contact. When the input signal contact X is closed, the timer 1 closes the contact 2 and outputs the output signal Y after a lapse of a set fixed time, and the control is continued.

[0003]

In such a conventional technique, when the timer 1 in the time relay has malfunctioned, the input signal contact X is closed, and even if the time set by the timer 1 elapses, the contacts are contacted. No output signal Y is output because 2 is not closed. The present invention has been made in view of the above problems, and an object of the present invention is to provide a time relay that operates normally even if a timer malfunctions.

[0004]

In order to achieve the above object, in the present invention, two systems of timers are prepared, and first timers are provided.
If the timer is defective, the second timer controls.

[0005]

When the first timer becomes defective, the second timer operates and outputs the output signal.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a time relay according to the present invention. In FIG. 1, 11 is a timer having a time setting time of T ₁ , 21 is a timer having a time setting time of T ₂ , 12 and 13 are time A and B contacts linked with the timer 11, and 22 and 23 are timer 21. It is the A contact and the B contact for the timed period that is interlocked.

The timers 11 and 21 are connected in parallel. The B contact 23 is connected to the timer 11 and the B contact 13 is connected to the timer 21 in series. The A contacts 12 and 22 for controlling the output signal are connected in parallel.
2 is a time chart explaining the operation of the time relay according to the present invention. First, a case where the timer 11 operates normally will be described. When the input signal contact X is closed at time T ₀ in FIG.
And the contact 12 is closed and the output signal Y is output after the time set time T ₁ of the timer 11 has elapsed. Timer 11
To set the time T ₁ of the so towards the setting of the timer 21 times T ₂ becomes longer, is set as T ₁ <T _2. Therefore, the contact 13 is opened before the operation of the timer 21 starts, that is, when the time T ₁ has elapsed, and the timer 21 becomes inoperative.

Next, a case where the timer 11 does not operate normally will be described. At time T ₀ in FIG. 2B,
Even if the input signal contact X is closed, the timer 11 does not operate because it is defective, and the contact 12 remains open and the contact 13 also remains closed even after the time set time T ₁ of the timer 11 has elapsed. In this state, the output signal Y is not output, but when the time set time T ₂ of the timer 21 elapses, the contact 23 is opened and the contact 22 is closed to output the output signal Y. Here, the contact 23 is opened and the timer 11
It is a timer 1 that has caused a defect
This is to prevent the 1 from suddenly operating and the temperature in the timer 11 from rising.

[0009]

The first timer according to the prior art is added,
By providing the second timer, even if the first timer malfunctions, an output signal can be output and control can be continued.

[Brief description of drawings]

FIG. 1 is a block diagram of a time relay according to the present invention.

FIG. 2 is a time chart of the time relay according to the present invention.

FIG. 3 is a block diagram of a conventional time relay.

[Explanation of symbols]

1 timer 2 contact 11 timer 12 A contact 13 B contact 21 timer 22 A contact 23 B contact X input signal contact T ₀ signal input time T ₁ time setting time of timer 11 time setting time of T ₂ timer 21

Claims (2)

[Claims] 1. A parallel circuit of a first timer having a fixed time-setting time and a second timer having a time-setting time longer than the time-setting time of the first timer, and connected between power supplies via an input signal contact. A time relay which is connected and obtains an output signal from a parallel circuit of a first contact interlocking with the first timer and a second contact interlocking with the second timer. 2. The time relay according to claim 1, wherein said first timer has a third contact interlocking with a second timer and said second timer has a fourth contact interlocking with a first timer. A timed relay characterized by connecting contacts in series.