Cat Digital Voltage Regulator (CDVR)
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| Illustration 1 | g01115009 |
The Cat Digital Voltage Regulator (CDVR) is a microprocessor-based voltage regulator. Control power for the CDVR is supplied from an external 24 DCV source. The power stage of the CDVR can be supplied from a multi-pole, high frequency, permanent magnet generator (PMG), from the generator output (shunt excitation). The power stage of the CDVR can also be supplied from auxiliary windings (AREP) that are included on some generators. Connections to the CDVR are made through three plug type connectors. The communication between the CDVR and a service tool is accomplished using a CANBUS protocol.
The CDVR has the following features:
- Three control modes:
- Automatic voltage regulation (AVR)
- Power factor (PF) regulation
- Reactive power (VAR) regulation
- Programmable stability settings
- Soft start control with an adjustable time setting in AVR mode
- Dual slope voltage versus frequency (V/Hz) characteristic
- Three-phase or single-phase voltage sensing
- Single-phase current sensing
- Field current and field voltage sensing
- Ten protection functions
Adjusting the CDVR
In order to view and configure the parameters of the CDVR, a PC with the Cat PC software is required.
Voltage sensing for the CDVR is also achieved via an internal switch located on the chassis of the top control panel box. The unit must not be running when the voltage switch is changed. When changing between three-phase and single-phase voltage, the EMCP flash file setting for sensing type will need to be changed using Cat electronic technician.
Refer to Specifications, Systems Operation, Testing and Adjusting, RENR7941, "Cat Digital Voltage Regulator (CDVR)" for complete information.
Integrated Voltage Regulator (IVR)
The Integrated Voltage Regulator (IVR) provides excitation current to the generator. The IVR is controlled by the IVR function in the EMCP4. The IVR function allows the EMCP4 to control the generator voltage, optimize transient performance, and provide feature specification.
The excitation module may interface with any of the following excitation systems: Self Excitation (SE), Internal Excitation (IE) and Permanent Magnet (PMG) excitation systems.
For additional information about the IVR, see Application and Installation, LEBE0006, and Special Instruction, REHS9106.
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| Illustration 2 | g03712568 |
Excitation Module 10 (EM10) (1) Connector P3 (2) Connector P2 (3) Connector P4 | |
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.
| 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.
| 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.
| 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.
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| Illustration 3 | g03487998 |
Under-frequency (loading) profile slope1 = 1.0 V/Hz, slope2 = 2.0 V/Hz | |