TACHOMETER 8T9872 - Caterpillar

Illustration 1 g00776704
Block Diagram of the Generator Monitoring System (GMS)The Generator Monitoring System (GMS) is an engine protection and monitoring system. The GMS is designed for 3600 genset engines. The combined weight of the GMS and mounted sensors is approximately 90 kg (198 lb). The powermonitor PM3000 is optional. The PM3000 weighs 2.0 kg (4.41 lb).The GMS displays the following parameters: line voltages, line amperages, total power, power factor (PF) and frequency.The GMS consists of the following components:
Generator Control Panel
Generator Mounted Sensors
Engine Mounted Sensors and associated wiring
Powermonitor PM3000 (optional)Generator Control Panel
The Generator Control Panel contains the following components:
control switches
programmable logic controller (PLC)
minimum protection backup relay system____________________Control Switches - Control switches are used to start the engine and to stop the engine. The following control switches are located on the Generator Control Panel:
"EMERGENCY STOP" button
"OFF/RESET-LOCAL-REMOTE" switch
"PRELUBE-RUN-START" switch
"FUEL CONTROL" switch
"HORN SILENCE-LAMP TEST" switchThe following control switches depend on the option of governor that is selected:
"IDLE/RATED" switch
"SPEED CONTROL" potentiometer
"RAISE/LOWER" switch____________________Programmable Logic Controller (PLC) - The PLC provides complete monitoring and control for the 3600 Caterpillar engines. The programmable logic controller is the computer that conducts the following engine functions: control, monitoring and protection. A display on the programmable logic controller provides the engine status for the operator. The basic modular programmable logic controller consists of the following components:
power supply
Central Processing Unit (CPU)
chassis
input modules (discrete and analog)
output modules (discrete)
engine speed switchThe power supply delivers a voltage for the following components: the CPU, the chassis and the input and the output modules that are mounted on the chassis. An input of 24 VDC is typically provided by a battery set. The power supply has the following features: isolation from ground, ability to handle lower battery voltage and immunity from noise.The Central Processing Unit (CPU) module in the programmable logic controller. The CPU contains the software that controls the behavior of the programmable logic controller. The CPU module provides the intelligence for the system. The program for the system resides in the CPU module.There are two types of input modules: discrete and analog. The discrete input modules consist of digital input modules that are used to determine whether a circuit is ON or OFF. The analog input modules have voltage input that can vary within a fixed range. The analog input modules are the following: thermocouple module, resistance temperature detectors (RTD) modules and the 4-20 mA modules.The AMCI module is an analog input card that measures frequency. The PLC converts the frequency to engine speed RPM. The engine speed sensor and the turbocharger speed pickup provide input to this module.The output modules are discrete output modules that have 16 digital outputs. The output modules provide voltage control. The output modules provide power for the following functions: energizing the lamps, energizing the relays, energizing the fuel shutoff solenoid and energizing the air shutoff solenoid.The engine speed switch accepts a signal from the engine speed sensor. The engine speed sensor is mounted on the engine. The speed switch determines the engine speed from the signal. The speed