ACCESSORY DRIVE 7L0260 - Caterpillar

EMCP IVR Connection
To regulate the generator terminal voltage, the EMCP communicates the desired excitation command to the excitation module through a pulse width modulation (PWM) signal. A twisted pair of shielded cable must be used for the communication link. Table 1 details the connections to be made between the EMCP and Excitation Module.
Table 1
EMCP 4.1 and EMCP 4.2 Connections to Excitation Module (70-pin connector)
EMCP 4.1 and EMCP 4.2 70-Pin Connector Excitation Module 3-Pin Connector
Digital Output #2 / IVR CS+ 68 CS+ P3-2
Battery negative splice 60 or 65 CS- P3-3
Battery negative splice 60 or 65 Shield P3-1
EMCP 4.3 and EMCP 4.4 Connections to Excitation Module (120-pin connector)
EMCP 4.3 and EMCP 4.4 120-Pin Connector Excitation Module 3-Pin Connector
PWM Output #2 Positive 28 CS+ P3-2
PWM Output #2 Negative 8 CS- P3-3
Shield 19 Shield P3-1 Table 2 provides information on the technical specification of the EM10 and EM15 modules. Selection of the appropriate module must be determined by the following:
Nominal and maximum generator excitation current at full load (standby 0.8 PF).
The maximum AC voltage input.
Table 2
EM10 and EM15 Technical Specifications
EM10 EM15
Compatible Generator Excitation Types Permanent Magnet (PM) Self-Excitation (SE) Internal Excitation (IE/AREP)(1)
Nominal Field Current Output 6A 7A
Maximum (forcing) Field Current Output 10A 15A
Maximum AC Voltage Input 180Vms 240Vms
(1) Internal Excitation (IE is also referred to as “Auxiliary Regulation Excitation Principle”(AREP)IVR Excitation Module Connections
The EM10 and EM15 excitation modules have three plug type multiple-pin connectors. The connectors are labeled P2, P3, and P4 as shown in illustration 2. Table 3 describes the signal and function of each connector pin.
Table 3
Excitation Module Connections
Terminal Label Signal/Function
P2-1 F+ Exciter Field Positive
P2-2 F- Exciter Field Negative
P3-1 Shield Excitation Command Control Signal Shield
P3-2 CS+ Excitation Command Control Signal Positive
P3-3 CS- Excitation Command Control Signal Negative
P4-1 X2 Excitation Power Supply Input X2
P4-2 Z1 Excitation Power Supply Input Z1
P4-3 X1 Excitation Power Supply Input X1
P4-4 Z2 Excitation Power Supply Input Z2 Note: The X2 and Z1 connections are internally linked within the excitation module. The link provides a point of common connection for the auxiliary windings where an AREP or IE excitation supply is available. Also, the X2 and Z1 connections may be linked externally to the excitation module. Only three connections (X1, X2, and Z2) are needed for the EM. Refer to Systems Operation/Test and Adjust/Troubleshooting, UENR1209, "Integrated Voltage Regulator Connections" for excitation module wiring connections. The wiring diagrams are for self-excitation (shunt), auxiliary windings (AREP/IE), and permanent magnet (PM) configurations.The voltage regulator knee frequency must be configured for your specific package requirements. The knee frequency for 50 Hz operation will usually be between 48.0 and 49.8 Hz. For 60 Hz operation, the parameter must be set between 58.0 to 59.8 Hz.Refer to Illustration 3 for an example under-frequency roll-off (loading) profile.
Illustration 3 g03487998
Under-frequency (loading) profile slope1 = 1.0 V/Hz, slope2 = 2.0 V/Hz
EM 10 Excitation Module
Illustration 4 g03457036The EM 10 excitation module provides excitation current to the generator, and is controlled by the IVR function in the EMCP 4 controls.Over-excitation Protection
Illustration 5 g03457278
If a short-circuit fault occurs at the generator terminals, the