Cummins PCC 3.3, PCC 2.3 and Cat EMCP 4.4 Controllers

Short answer

The Cummins PowerCommand controllers (PCC 1.1, PCC 2.3 and PCC 3.3) and the Caterpillar EMCP 4 controllers (EMCP 4.2 and EMCP 4.4) come mounted on the generator set and run it: start and stop, engine and alternator protection, metering and, on the paralleling models, synchronizing and load sharing. They connect to SCADA or the building management system over Modbus.

What it is and where it is used

The Cummins PowerCommand PCC 1.1, PCC 2.3 and PCC 3.3 and the Caterpillar EMCP 4.2 and EMCP 4.4 are the controllers fitted at the factory on gensets from those two brands. They start and stop the engine, watch oil pressure, temperature and speed, measure the alternator voltage, frequency and power, and trip the generator breaker on a fault. The paralleling models also synchronize with other gensets or with the utility and share the load. The IEEE 519 harmonic limits (point of common coupling, THD and TDD) are explained in IEEE 519 harmonic limits.

They are found in emergency plants at hospitals, buildings and data centers, in industry with on-site generation, and in substation station service. Alongside them is the Kohler Decision-Maker, the controller on Kohler gensets. For the complete system see emergency diesel plant; for controllers from other brands that are mounted in panels, see Deep Sea and SmartGen controllers.

Variants: PCC 1.1, PCC 2.3, PCC 3.3, EMCP 4.2, EMCP 4.2B and EMCP 4.4

Model	Application	Main difference
Cummins PowerCommand PCC 1.1	Single genset	Basic start, stop and protection control
Cummins PowerCommand PCC 2.3	Single genset, external transfer switch	More metering, alarms and Modbus communication
Cummins PowerCommand PCC 3.3	Paralleled gensets and utility paralleling	Synchronizing, load sharing and paralleling between gensets
Cummins DMC (Digital Master Control)	Multi-genset system	Master paralleling control in a panel, with Modbus TCP
Caterpillar EMCP 4.2 and EMCP 4.2B	Single genset	Genset control and protection
Caterpillar EMCP 4.4	Paralleled gensets and utility paralleling	Paralleling, load sharing and dead-bus arbitration
Kohler Decision-Maker	Kohler gensets	Brand-specific controller

Cummins states that the PCC 3.3 can replace earlier controls (PCC 1.x, PCC 2.x, PCC 3100 and Detector) as a field upgrade. Caterpillar offers upgrade kits for the EMCP 4 family and remanufactured EMCP 4.2, 4.2B, 4.3 and 4.4 units.

Main features

Engine control: start sequence, cooldown, stop and emergency stop, with communication to the engine electronics.
Alternator protection: overcurrent, voltage, frequency and reverse power on the models that include it. These functions protect the machine, but they do not replace the relay at the point of connection when the genset runs in parallel with the utility. See synchronous generator and its protection.
Paralleling (PCC 3.3 and EMCP 4.4): synchronizing, genset breaker closing, active and reactive power sharing, and island or utility-parallel operation.
Alarm and event log for fault analysis.

What a PowerCommand 3.3 offers, according to the Cummins specification sheet

The specification sheet for a gas genset with PowerCommand 3.3 (document A042J415, 2017) describes the control as a microprocessor-based system that integrates voltage regulation, engine and alternator protection, an operator interface and isochronous governing. The published data are these:

Digital voltage regulation with three-phase, four-wire sensing and PWM output, and digital isochronous governing.
AmpSentry, the integrated alternator protective relay. It includes overcurrent and short-circuit (trip), overcurrent warning, single-phase and three-phase fault regulation, and high and low voltage and frequency with trip. It adds an overload warning with alarm contact, reverse power and reverse kvar, and field overload. It also carries an «AMM» provision for arc flash risk, listed that way in the sheet.
Engine protection: oil pressure, coolant temperature and level, overspeed, fail to start, starter lockout, sensor failure, battery monitoring and test, and communication with the engine electronics.
Paralleling: first-start arbitration for closing to the bus, phase-lock-loop synchronizer with voltage matching, sync-check relay and isochronous kW and kvar load sharing. It includes load control for paralleling with the utility and an extended paralleling mode (base load or peak shaving). The digital transfer control supports open transition, closed transition, closed transition with ramp, peak shaving and base load.
Logging: a 32-fault history, load profile by operating hours, fault data and simulation with the InPower service tool, a real-time clock with date stamp and 20 configurable inputs and outputs.
Interface: 320 by 240 pixel graphic display, English, Spanish and French as standard, and PCCNet and Modbus communications as standard. Options include the PowerCommand Aux 101 and 102 network modules and a Modbus-to-BACnet module.

The same sheet notes that the genset meets UL, CSA and CE prototype tests. It also explains the ISO 8528 power ratings: ESP (emergency standby power, for the duration of a utility outage), PRP (prime power, unlimited hours with variable load) and COP (continuous base load). Whether a sheet says «standby» or «prime» changes the sizing and the permitted use of the genset.

What changes with the Caterpillar EMCP 4

The data given here come from Cat dealers, not from a manufacturer sheet, and must be confirmed against the manual for your version:

The EMCP 4.3 is described with Modbus RTU data links, Modbus TCP over Ethernet for SCADA, and links for annunciators and accessory modules.
The family supports expansion modules: remote annunciators (CAN and serial), a digital input and output module, an RTD module and a thermocouple module.
The EMCP 4.4 adds paralleling of several gensets, or of one genset with the utility, and bus phase-sequence protection.

Points to watch when integrating and replacing

Genset protection versus connection protection. The controller protections look after the alternator and the engine. When the genset is connected in parallel with the utility, the interconnection functions (frequency, voltage, anti-islanding, reverse power) are required by the utility and are tested with independent equipment. See protection requirements for distributed generation.
Backfeed to the grid. The Cummins sheet warns that returning power to a utility grid can cause electrocution and that a genset must not be connected to a building installation without an approved device or with the main disconnect closed. Automatic source transfer is part of that safety; see automatic transfer switches.
Replacing old controls. Replacing a PCC 1.x, 2.x or a Detector with a PCC 3.3 is a field upgrade that Cummins describes, but it changes the wiring, the inputs and the Modbus maps; those changes must be reflected in SCADA and in the drawings.
Modbus maps. Each firmware version can change addresses and scaling. Before integrating, request the map for the installed version and validate each point with a field reading.
Functional test. Starting under real load, the transfer and the shutdown on a simulated fault are the tests that tell you whether the whole system works; a correct reading on the display does not replace them.

Communications and integration

Both manufacturers publish Modbus register maps for their controllers; on some models network access goes through an optional communication module. The EMCP 4.4 master panel connects to the building system over Modbus RS-485 or Ethernet, and Cummins DMCs over Modbus TCP. Configuration is done with each manufacturer’s service software. See Modbus RTU and TCP and automatic transfer switches.

Frequent technical questions

How do I get the PCC 3.3 and EMCP 4.2 manuals? Ask the manufacturer or its dealer, giving the exact part number and firmware version.
Where is the EMCP 4.2 wiring diagram? The wiring diagram depends on the genset and the panel; the manufacturer’s diagram is the starting point, but the as-built panel drawing governs.
The genset starts but does not take load: the cause is usually in the transfer logic, in the breaker close permissive or in synchronizing, not in the engine.
Paralleling with the utility: besides the controller, the utility requires protection and studies at the point of connection. See generator in parallel with the grid.

How we help

We do not sell or repair engines. At Tiza Group we configure the integration of the controller into SCADA or the control system, review the transfer and paralleling logic, and verify the protection of the generator and of the point of connection, in substations and in industry. See control, protection and communications configuration and, for integration over Modbus or IEC 61850, SCADA integration and gateways. If you are going to parallel the genset with the utility, we perform the commissioning and its tests, in Colombia or elsewhere on request, as described in testing and commissioning. Write to us through the contact page.

References

Cummins, PowerCommand 3.3 upgrade sheet, genset data sheets with PowerCommand 2.2/3.3 and the DMC2000 Digital Master Control.
Caterpillar, EMCP 4 Generator Set Controls product page (cat.com) and EMCP 4.4 master panel sheets published by Cat dealers.
ISO 8528, reciprocating internal combustion engine driven alternating current generating sets.

Frequently asked questions

What is the difference between the Cummins PCC 2.3 and PCC 3.3?

Both are PowerCommand controllers mounted on the generator set. Cummins presents the PCC 3.3 as the control with full paralleling: it synchronizes, shares load and allows paralleling between gensets with motorized breakers. The PCC 2.3 is used on gensets that run alone or with an external transfer switch. The exact function depends on the version and the installed options.

Can the EMCP 4.4 parallel several generators?

Yes. Caterpillar offers the EMCP 4.4 for paralleling several gensets with each other and with the utility, with load sharing and dead-bus arbitration, plus a master supervision panel to centralize several gensets. The EMCP 4.2 and EMCP 4.2B are used on gensets that run alone.

Where can I get the EMCP 4.2 manual?

Caterpillar supplies the EMCP 4 operation manuals and wiring diagrams through its dealer network and its service portal; Cummins does the same for PowerCommand through its documentation portal. Before ordering, note the exact controller part number and firmware version, because they change between revisions.