CONTROL PANEL SR4 GENERATOR MOUNTED Caterpillar


Optional Components

Usage:


Control Panel
(3) Frequency meter. (4) DC voltmeter. (6) Ammeter voltmeter phase selector switch. (8) Panel light switch. (9) Emergency stop push button. (10) Voltage adjust rheostat. (11) Governor Switch.

Frequency Meter

The frequency meter shows the frequency in hertz (cycles per second) of the electricity made when the generator set is in operation. There is a direct relation between the frequency of the electricity and the rpm of the generator set, as shown in the following formula:

NOTE: An optional frequency meter resistor is required for generator operating voltages exceeding 240 VAC.

Voltage Adjustment Rheostat

The voltage adjust rheostat is located on the panel below the voltmeter. It is used to adjust the voltage output of the generator. This rheostat takes the place of the voltage level rheostat located on the generator voltage regulator assembly.

NOTE: When the optional rheostat is used on VR3 and VR4 regulators, the jumper wire connecting terminal four and terminal seven is removed.

Emergency Stop Push Button

This button is red in color. It is used to shutdown the engine in an emergency. If the emergency stop push button (ESPB) is used, the overspeed light (OSL) will light. The OSL and any other fault lights cannot be reset by way of the engine control switch while the ESPB is in. After the ESPB is pushed in, it will remain pushed in until reset.

------ WARNING! ------

To prevent personal injury due to accidental starting of the engine, disconnect the batteries before doing maintenance or repair work.

--------WARNING!------

To reset the ESPB, rotate the knob in the direction shown on the ESPB. The button will then move out from the panel.

Ammeter-Voltmeter Selector Switch

The ammeter-voltmeter selector (AVS) switch has four positions. In the zero position AVS switch contacts (9-10), (13-14) and (17-18) are closed. There is no reading on either the voltmeter or ammeter. See AC schematic (with optional ammeter, frequency meter and AVS)

When the AVS is in position one, contacts (3-4), (5-6), (11-12), (13-14) and (17-18) are closed. The voltmeter will indicate the potential difference between T1 and T2. The ammeter will indicate the current flowing in phase 1 (T1/U).

When the AVS is in position two, contacts (1-2), (7-8), (9-10), (15-16) and (17-18) are closed. The voltmeter will indicate the potential difference between T2 and T3. The ammeter will indicate the current flowing in phase 2 (T2/V).

When the AVS is in position three, contacts (5-6), (7-8), (9-10), (13-14) and (19-20) are closed. The voltmeter will indicate the potential difference between T1 and T3. The ammeter will indicate the current flowing in phase 3 (T3/W).

AC Ammeter

The AC ammeter gives an indication, in amperes, of the current from each phase of the generator to the load. The AVS connects the ammeter to the current transformers (CT1, CT2 or CT3) on phases (T1/U, T2/V or T3/W) respectively. The CT's transform the actual line current, in its respective phase lead, to a level (approximately 0 to 5 amperes) within the input range of the ammeter. The ammeter is calibrated to give an indication of the actual current flow in one phase of the generator.

Voltage Regulators

For information on the VR4 voltage regulator see SENR3906. For information on the VR3 voltage regulator see SENR3473.

DC Voltmeter

The DC voltmeter may be installed when the generator set engine is equipped with an alternator charging circuit. The DC voltmeter indicates the charging voltage to the battery. The DC voltmeter is turned on when the engine control switch is in the AUTO, START or STOP positions.

Governor Switch

The governor switch may be installed for use with Hydra-Mechanical and PSG governors equipped with synchronizing motors. After crank termination, the governor switch is enabled, permitting a change in engine rpm. Move the switch up to increase rpm, down to decrease rpm.

Panel Lights

Two panel illumination lights are located on each side at the top of the panel. They are turned ON and OFF by the panel light switch, which is located on the left side of the panel. The panel lights can be operated at any time regardless of ECS position or engine status.

Latching Fuel Solenoid

The latching fuel solenoid is located on the fuel injection pump of the engine. There are three leads on the latching solenoid, (start, stop and ground). When starting the engine, current is momentarily sent through the start lead energizing the solenoid. A special mechanical latching mechanism holds the solenoid in this position until current is sent through the stop lead.

General System Operation

The automatic start/stop system is normally used for standby operation. The generator set must start, pick up the load, operate at load, and stop after the load is removed. An automatic transfer switch controls the transfer of load to and from the generator set. When normal (commercial or utility supplied) power has a failure, initiating contact (IC) which is part of the automatic transfer switch, closes. This will begin the automatic start sequence. When the engine starts, the control panel instruments will show voltage and frequency. The automatic transfer switch will transfer the load to the generator set when voltage and frequency reach approximately rated value. When normal power returns, the automatic transfer switch will transfer the load back to normal power and the initiating contact (IC) will open. This will begin the automatic stop sequence. The generator set will also stop automatically if the engine has a failure.

The automatic start/stop panel will shut down the generator set when an engine fault occurs. At the same time, it will indicate by a fault lamp whether the fault is due to high water temperature, low oil pressure, overcrank or overspeed.

The automatic start/stop panel can be used on engine systems that are energized to shutoff, energized to run or have a latching fuel solenoid installed.

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