摘要:
A boiler control system utilizing a microcomputer, a memory, and a firing rate control scheme provides a boiler with a more responsive control arrangement. This improved response is accomplished by the firing rate control converting the desired pressure setpoint to a computer temperature, and then establishing a computed pressure band for control of the boiler.
摘要:
A boiler control system utilizing a microcomputer, a memory, and a firing rate control scheme provides a boiler with a more responsive control arrangement. This improved response is accomplished by the firing rate control converting the desired pressure setpoint to a computer temperature, and then establishing a computed pressure band for control of the boiler.
摘要:
A positive voltage supply (11, 12) is connected to a circuit having a single capacitor (14) and a depletiontype field-effect transistor (20) to create a simple and reliable timer (10). The capacitor is initially charged upon the opening of a control switch (30) without creating a timed output across the drain-source terminals (21, 22) of the field-effect transistor (20). The closing of the control switch (30) reverses the bias of the single capacitor (14) to the gate-source connections (23-22) of the field-effect transistor (20) to thereby create a fixed and reliable timed interval.
摘要:
Control potentiometers (10) are monitored by using a computer processor (18) and a monitor interface circuit connected between the potentiometer and the processor. The potentiometer, its terminals and its wiper (14) are monitored for faults. In addition the monitor interface circuit itself is tested so that a fault in the potentiometer or a fault in the monitor interface circuit is detected to prevent the control potentiometer and monitor interface circuit from producing an incorrect control signal. The monitoring is accomplished by measuring changes in the full potentiometer resistance from a predetermined value. The changes are compared against boundary limits to detect whether a change is inside or outside the boundary limits. A fault in the control potentiometer is indicated when a change is outside the boundary limits. The monitoring also monitors wiper resistance of the potentiometer. The wiper resistance of the control potentiometer is measured, and the wiper resistance is compared against a fault threshold to detect if the wiper resistance has passed the fault threshold. A fault in the wiper of the control potentiometer is indicated when the wiper resistance has passed the threshold. The testing of the monitor interface circuit is accomplished by measuring idle signals applied to the full potentiometer and to the wiper when the monitor interface circuit is an idle state. The idle signals are compared against an expected signal to detect if the idle signals are within a predetermined tolerance range of the expected signal. A fault in the monitor interface circuit is indicated if the idle signals are outside the predetermined tolerance range.
摘要:
Control potentiometers are monitored by using a computer processor and a monitor interface circuit connected between the potentiometer and the processor. The potentiometer, its terminals and its wiper are monitored for faults. In addition the monitor interface circuit itself is tested so that a fault in the potentiometer or a fault in the monitor interface circuit is detected to prevent the control potentiometer and monitor interface circuit from producing an incorrect control signal. The monitoring is accomplished by measuring changes in the full potentiometer resistance from a predetermined value. The changes are compared against boundary limits to detect whether a change is inside or outside the boundary limits. A fault in the control potentiometer is indicated when a change is outside the boundary limits. The monitoring also monitors wiper resistance of the potentiometer. The wiper resistance of the control potentiometer is measured, and the wiper resistance is compared against a fault threshold to detect if the wiper resistance has passed the fault threshold. A fault in the wiper of the control potentiometer is indicated when the wiper resistance has passed the threshold. The testing of the monitor interface circuit is accomplished by measuring idle signals applied to the full potentiometer and to the wiper when the monitor interface circuit is an idle state. The idle signals are compared against an expected signal to detect if the idle signals are within a predetermined tolerance range of the expected signal. A fault in the monitor interface circuit is indicated if the idle signals are outside the predetermined tolerance range.
摘要:
A boiler control (20) utilizing a pressure sensor (22, 23) is provided that operates the system in the low fire mode if the load is light and can be satisfied in that mode. If the low fire operation is inadequate to hold the load, and the pressure drops, the boiler is then operated in a modulating mode which includes a high fire limit.