3606, 3608, 3612 and 3616 Engines and C280-12, C280-16, C280-6 and C280-8 Marine Engines Generator Monitoring System Caterpillar

The GMS is equipped with two parallel engine overspeed devices. The two devices are the engine speed switch and the Programmable Logic Control. The overspeed setpoint is 113 percent of the rated speed of the engine. For example, an engine that has a 900 rpm rating will have an overspeed setpoint of 1017 rpm. A magnetic pickup sensor is used in order to send a signal to the engine speed switch and the PLC. The frequency of the magnetic pickup sensor is based on the number of flywheel teeth. The equivalent frequency at 1017 rpm is 4322 Hz.

Note: On-site testing of the maximum approved engine overspeed is not recommended due to the use of non-Caterpillar input devices. Therefore, the engine overspeed should NOT be tested above 1050 rpm.

Note: When you are simulating the engine speed in the following procedures, ensure that the fuel control switch on the control panel is in the ON position. After reaching the overspeed condition, the air shutoff will close. The air shutoff must be moved back to the normal operating position. The engine will not start when the air shutoff is closed. After an overspeed condition occurs, the "OFF/RESET" switch must also be switched to the RESET position before the engine will start.

Overspeed Test

1. Test the engine speed switch at 75 percent of the overspeed setting.

   1. While the engine is running, increase the engine speed above 75 percent of the overspeed setting. Alternately connect a 163-0096 Diagnostic and Calibration Tool to the engine speed switch in order to simulate engine speed. See Table 1 for speeds and frequencies.

   2. Connect the jumper wire for 75 percent verify in the engine speed switch. The engine will shut down. Output 0 of the engine speed switch will turn on.

   3. In order to reset the engine speed switch, turn the engine control switch to the "Off/Reset" position.

2. Test the engine speed switch and the PLC at the overspeed setting.

   1. Use the following step for an engine that is rated below 930 RPM:

      While the engine is running, increase the engine speed to the overspeed setting. Once the engine is within 25 rpm of the overspeed setting, slowly raise the engine speed. This is done in order to determine the engine speed at shutdown. The PLC and the engine speed switch work in parallel. Either the PLC or the engine speed switch will shut down the engine in this test.

      Use the following step for an engine that is rated above 930 RPM:

      Alternately connect a 163-0096 Diagnostic and Calibration Tool to the engine speed switch in order to simulate the engine speed. See Table 1 for speeds and frequencies.

   2. If the engine speed switch shuts down the engine due to an overspeed condition, the output 0 on the engine speed switch will illuminate.

      If this happens, press the "RESET" button on the engine speed switch in order to allow the engine to start again.

   3. In order to reset the engine speed switch, turn the engine control switch to the "Off/Reset" position.

3. Simulate the overspeed test for the PLC.

   1. Connect the positive lead of the frequency generator to terminal 222 and the negative lead to terminal 223. See Table 1 for speeds and frequencies.

   2. Increase the frequency until the overspeed setting is reached.

Table 1

Rated Speed (RPM)	Overspeed Setting (RPM)	Overspeed Setting (Frequency)	75 Percent Of Overspeed Setting (RPM)	75 Percent Of Overspeed Setting (Frequency)
720	814	3458	610	2593
750	848	3602	636	2701
900	1017	4322	763	3242
930	1051	4467	788	3350
1000	1130	4803	848	3602
1050	1187	5045	890	3784