JPH0145521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a boiler feed water pump control device that enables fail-safe operation of an automatic boiler controller.

Conventionally, there has been a device of this type as shown in FIG. In the figure, 1 is a boiler feed water pump turbine (hereinafter abbreviated as BFPT) torque motor control device, 2 is a current-voltage converter, 3 is an operational amplifier, and 4
5 is a booster amplifier that amplifies the voltage amplified by the operational amplifier 3, and 5 is a failure detection circuit on the regular side of the control circuit equipped with dual functions for regular use and standby. Similarly, 6 is a failure detection circuit on the backup side. 7 is a regular use standby switching relay that is operated by the output signal of the regular side failure detection circuit 5; 8 is a torque motor that drives the water supply pump turbine; 9 is an automatic boiler controller (hereinafter abbreviated as ABC);
A BFPT control signal 10 is output.

Next, the operation shown in FIG. 1 will be explained. First, as a steady state operation, BFPT control signal 10 is sent from ABC9.
An opening command signal having a current level width of about 0 to 20 mA is given to the current-voltage converter 2. Next, the current input signal is converted into a voltage signal by a current-voltage converter 2, and then input to an operational amplifier 3 for voltage signal amplification. The output voltage level of operational amplifier 3 is 0~
At 100%, it is amplified to about 0 to -10V, and the output signal is given to the booster amplifier 4 at the subsequent stage. The booster amplifier 4 performs current amplification,
Its output voltage is BFPT which is the output of ABC9.
Control signal, that is, opening command signal 0 to 100% (4
~20mA) corresponding to the current output signal (0~250mA)
A).

The output signal of the booster amplifier 4 is given to the coil of the torque motor 8 via the regular standby switching relay 7.
Execute automatic control of BFPT. In such a state, when the regular side failure detection circuit 5 detects a failure in the regular side circuit, it immediately transmits a failure detection signal to the regular use standby switching relay 7, and switches the input signal path of the BFPT control signal 10 to the standby side. In this way, the operation of the BFPT torque motor is continued without stopping the operating function, and during this time the fault in the control circuit on the regular side is repaired. The standby side control circuit also performs the same function as the regular side control circuit, and if a failure in its own circuit is detected during operation of the standby control circuit, it immediately sends a signal to the regular standby switching relay 7 in the same manner as described above. is transmitted and switched to the repaired normal use side control circuit.

Since the conventional boiler feed water pump control device was configured as described above, it is equipped with a double-function fail-safe function against internal failures of the BFPT torque motor control device 1, but failures such as loss of power inside ABC are equipped. Because no special fail-safe considerations were taken in the event of an outbreak, ABC
The BFPT control signal 10 is completely cut off and becomes an abnormal signal, and the control function of the BFPT torque motor outputs an abnormal output, making it difficult to continue operating the plant, and in some cases, producing a large number of defective products. There were some shortcomings.

This invention was made in order to eliminate the drawbacks of the conventional ones as described above, and even if a power failure etc. occurs in the ABC, the BFPT torque motor output current is maintained at the output current immediately before the failure, and the plant The purpose of the present invention is to provide a boiler feed water pump control device that enables continuous operation of boiler water pumps, etc.

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, the same parts as in FIG. 1 are designated by the same reference numerals.
3D is an operational amplifier; in particular, 3C is an integrating type operational amplifier equipped with an integrating capacitor C, and an analog memory circuit AM is constituted by three sets of operational amplifiers 3B, 3C, and 3D. Reference numeral 11 denotes an ABC failure detection relay operated by an ABC failure signal 12, and has a contact Fa.

Next, the operation of the present invention will be explained below. When the power source of ABC9 is normal, the analog memory circuit AM constituted by operational amplifiers 3B, 3C, and 3D does not output the ABC failure signal 12, and the ABC failure detection relay 11 is in an energized state. Therefore, the contact Fa is closed,
The output signal has a first-order lag characteristic change with respect to the input signal from the BFPT control signal 10. If the gain of the operational amplifier 3B is made extremely large, the time constant of the analog memory circuit AM becomes extremely small, and it operates with such a high-speed response that it can be ignored in appearance.

On the other hand, when a failure occurs in the power supply of ABC 9 and the power is cut off, a failure detection signal is output from the ABC failure signal 12, the ABC failure detection relay 11 is operated, and the contact Fa is opened. However, even if the input signal is cut off, the integral type operational amplifier 3C of the analog memory circuit AM maintains the integral value by the capacitor C of the operational amplifier 3C, so the output signal of the analog memory circuit AM is immediately before the failure. The output signal of the analog memory circuit AM, which operates unchanged from before the failure, is transferred to the torque motor 8.
Continuously output.

As described above, according to the present invention, an analog memory circuit is provided in the standby side control circuit of the BFPT torque motor control device, and during normal operation, control signals during normal operation are stored in the analog memory circuit, and ABC is prevented from malfunctioning. When the failure detection circuit on the regular use side immediately transmits an output signal to the regular use standby switching relay, the stored signal of the analog memory circuit can be sent to the torque motor under the same conditions as the output signal immediately before the failure. This has the remarkable effect that even in the event of a failure, fail-safe operation can be continued at all times without causing fluctuations in the plant or the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional boiler feed water pump turbine torque motor control device, and FIG. 2 is a block diagram showing a boiler feed water pump turbine torque motor control device according to an embodiment of the present invention. 1...Boiler feed water pump turbine (BFPT)
Torque motor control device, 2... current voltage converter, 3... operational amplifier, 4... booster amplifier,
5... Regular side failure detection circuit, 6... Standby side failure detection circuit, 7... Regular use standby switching relay, 8... Torque motor, 9... Automatic boiler controller (ABC), 10... BFPT control signal ,
11...ABC failure detection relay, AM...analog memory circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A current-voltage converter that receives a boiler feed water pump turbine control signal of an automatic boiler controller and converts it into a voltage signal, and converts the output signal of the current-voltage converter into a first operational amplifier, a first a normal use side fault detection control circuit consisting of a booster amplifier and a normal use side failure detection circuit; a standby side consisting of a second operational amplifier receiving the output signal of the current-voltage converter and a second booster amplifier spare side failure detection circuit; In the boiler water supply control device, the output signals of the failure detection control circuit, the failure detection control circuit on the regular side and the failure detection control circuit on the standby side are connected to the regular use standby switching relay to finally drive the torque motor. When a power supply failure occurs in the boiler controller, the automatic boiler controller failure detection relay, which is driven by generating an automatic boiler controller failure signal, and the second operational amplifier of the standby side failure detection control circuit are connected to analog systems. an analog memory circuit constituted by a memory; and the analog memory circuit configured to provide a memory maintenance signal during normal operation immediately before a failure to the torque motor when the automatic boiler controller failure detection relay receives an automatic boiler controller failure signal. A boiler water supply control device characterized by having a changeover switch circuit installed inside. 2. The analog memory circuit is configured by three sets of operational amplifiers, one of which is an integral type operational amplifier, and the input signal circuit of the integral type operational amplifier is connected to an automatic boiler controller failure detection relay. Switching is possible using the output signal,
2. A boiler feed water control system according to claim 1, wherein the output signal of said integral type operational amplifier is used as a drive signal for a torque motor when a failure signal is output from an automatic boiler controller.