ARMY TM 9-6115-672-14 AIR FORCE TO 35C2-3-444-32 MARINE CORPS TM 09244A/09245A-14 1-16   TABLE 1-2.  PERFORMANCE CHARACTERISTICS (continued) MEP-806B MEP-816B 2.    Frequency (continued): f. Overshoot with application of load 4% of rated frequency (max.) 1.5% of rated frequency   (max.) Recovery time 2 seconds 1 second g.    Adjustment range 48-52 Hz, not below 45 Hz 390-420 Hz, not below 370 for 50 Hz operation Hz or above 430 Hz 58-62 Hz, not above 65 Hz for 60 Hz operation SECTION III. PRINCIPLES OF OPERATION 1.15 INTRODUCTION. This section contains functional descriptions of the generator set.  How the controls and indicators interact with the system is explained as well as the location and description of major components. 1.16 PRINCIPLES OF OPERATION. 1.16.1 Digital Control System (DCS). 1.16.1.1 The DCS is a closed-loop system providing the operator with real-time system status information and control.   It includes automatic shutdown features if critical components fail to protect the generator set from damage and to prevent damaging output power and voltage levels.  It includes a digital computer using software to process inputs from the generator set and from the operator.  The DCS accepts operator commands to adjust various generator set parameters such as frequency and voltage.  The DCS also facilitates operating two or more generator sets in parallel.  The DCS can be operated at the generator set or from a remote location using an IBM-compatible personal computer (PC) 1.16.1.2 In the event that the computer operating software is lost or operating incorrectly, the software must be restored.  Procedures are provided for restoring the CIM software locally in Paragraph 5.12 and TQG remote software restoration is found in Paragraph 2.13.2. 1.16.1.3 Eight major components or modules are included in the DCS: The DCS speed control unit, automatic voltage regulator, load sharing synchronizer, I/O interface module, backplane module, electric actuator, computer interface module (CIM), and keypad assembly.  The DCS provides multiple, integrated functions as the controller of the fault, governor, and voltage regulation systems, as described below. 1.16.1.4 The CIM is the primary operator interface with the DCS.  It is a self-contained IBM compatible computer with an AMD 486 processor running the Windows CE operating system.  An internally lit Liquid Crystal Display (LCD) screen provides the operator with status displays and control capability.  A cursor symbol on the display is controlled by the keypad assembly, which is a set of four arrow keys and a SELECT key to enter commands.  The load sharing synchronizer is used when paralleling the generator set to a main bus or to another generator set.  This module provides signals to the DCS speed control unit to adjust engine speed settings to maintain a match between the outputs of the two generator sets.  The I/O interface module controls and interfaces with all the other components in the DCS.  For example, it receives inputs from engine sensors and converts them for use by the CIM.  Most of the DCS signals, including control panel inputs, are routed through this module.  The status of the I/O interface module is indicated by a green HEARTBEAT light emitting diode (LED) which blinks at a rate of approximately two times per second to indicate the module is operational.