Generator Controllers & Control Modules

A generator controller is the electronic brain that manages all aspects of generator operation. Core functions: (1) Auto Start/Stop — monitors utility/mains power and automatically starts the generator during an outage, transfers load, and stops after utility returns; (2) Engine Protection — monitors oil pressure, coolant temperature, overspeed, underspeed, and battery voltage. Shuts down the engine on critical alarms with a logged fault code; (3) Generator Monitoring — measures and displays voltage (L-L, L-N), current (per phase), frequency, power (kW, kVA, PF), and energy (kWh); (4) Fuel Management — monitors fuel level and consumption rate; (5) Event Logging — records starts, stops, alarms, and maintenance reminders with timestamps; (6) Communication — RS485, CAN bus (J1939 for electronic engines), USB, and Ethernet for remote monitoring via SCADA/BMS. Advanced controllers add: load sharing, synchronizing, kW/VAr control, and PLC functionality. HUAQUAN supplies controllers from Deep Sea (DSE), ComAp, Datakom, SmartGen, and other leading brands.

HUAQUAN supplies controllers and modules from: Deep Sea Electronics (DSE) — DSE4520, DSE6020, DSE6110, DSE7320, DSE8610, DSE8660 and the full DSE range; ComAp — InteliLite (IL-NT), InteliGen (IG-NT), InteliSys (IS-NT), InteliMains (IM-NT); Datakom — DKG, D500, D700 series; SmartGen — HGM6100, HGM7100, HGM7200, HGM8200, HGM9500 series; Lovato — RGK series; Deif — AGC series; and Chinese OEM controllers (Weichai, Yuchai, SDEC). We supply complete controller kits including the controller module, wiring harness, current transformers (CTs), magnetic pickup (MPU / speed sensor), oil pressure and temperature sensors, and mounting hardware. We also provide pre-configured controllers programmed for specific engine/alternator combinations. Remote monitoring upgrades (GSM/4G modem, Ethernet gateway) are available for most controller platforms.

Controller no-start troubleshooting: (1) Check the controller display — is it powered on? If the LCD is blank, the controller has no DC power. Check the battery, battery disconnect switch, and controller DC fuse (typically 5-10A); (2) Read the controller's event log — scroll through alarms. Common start-inhibit alarms: 'Emergency Stop', 'Low Coolant Level', 'Low Oil Pressure' (pre-lubed engines — pressure must be above the pre-alarm threshold BEFORE starting), 'Battery Under Voltage'; (3) Place the controller in 'Manual' or 'Test' mode and press the Start button. Listen for the fuel solenoid clicking — if no click, check the controller's fuel output relay and wiring from the controller to the solenoid; (4) Check the controller's start output — use a multimeter on the controller's crank output terminal during the start attempt. It should output battery voltage. If not, the controller's crank relay or output transistor is faulty; (5) Verify the speed signal — many controllers will not enable fuel delivery if they don't detect engine rotation via the magnetic pickup (MPU). Measure the MPU output AC voltage during cranking — should be 2-5V AC minimum; (6) Check all controller configuration settings — a misconfigured 'Fail to Start' setting (e.g., 2-second crank time when the engine needs 5 seconds) will prevent starting; (7) If the controller attempts to start (cranking) but the engine doesn't fire, the issue is not the controller — troubleshoot fuel, compression, and engine speed.

Controller types by functionality: AMF (Auto Mains Failure) — the most basic automatic controller. Monitors mains supply, starts the generator on mains failure, and provides a signal to a separate transfer switch. Single generator only. Suitable for simple standby applications. ATS Controller (Auto Transfer Switch Controller) — combines AMF with integrated transfer switch control. Manages both the generator AND the transfer switch (mains-genset switching). Provides load voltage monitoring on both sources. Synchronizing Controller — manages multiple generators in parallel. Features: load sharing (kW and kVAr), speed and voltage bias control, dead bus detection, first-on arbitration, and synchronizing check (voltage, frequency, phase angle matching). Required when: (1) Multiple generators supply a common bus; (2) Generator-to-mains paralleling (peak shaving, base load); (3) Soft loading/unloading transition. The controller hierarchy from simple to complex: Manual Key Start < AMF < ATS Controller < Single Synchronizing < Multi-Gen Load Sharing < Full Power Management System.

Engine protection configuration guidelines: (1) Low Oil Pressure — Shutdown: 10-15 PSI below the engine's rated idle pressure. Typical settings: alarm at 15-20 PSI, shutdown at 10 PSI. Set a start delay of 10-15 seconds to allow pressure to build without false tripping; (2) High Coolant Temperature — Shutdown: 5-10 degrees C above the thermostat's fully-open temperature. Typical: alarm at 100 degrees C, shutdown at 105-110 degrees C; (3) Overspeed — Shutdown at 115% of rated speed (e.g., 1,725 RPM for a 1,500 RPM set). Overspeed is mechanical failure (governor runaway) — immediate shutdown, no delay; (4) Underspeed — Shutdown at 85% of rated speed with a 5-second delay to allow for load transients; (5) Battery — Alarm at 12.0V (12V system) or 24.0V (24V system) to warn of failing charger or battery; (6) Fail to Start — 3 crank attempts of 10-15 seconds each, with 20-30 second rest between attempts. After 3 failures, lock out and alarm. These settings protect your engine investment — aggressive settings may cause nuisance trips, but loose settings risk catastrophic engine damage.

Common communication protocols: (1) Modbus RTU (RS485) — industry standard for industrial automation. Two-wire serial, up to 1,200m range at 9,600 bps. Connect to SCADA, PLC, or BMS; (2) Modbus TCP/IP (Ethernet) — Modbus encapsulated in TCP packets, allows integration with Ethernet networks and web-based monitoring; (3) CAN bus / J1939 — the standard protocol for communication with electronic diesel engines. The controller reads engine parameters (RPM, temperatures, pressures, fault codes) directly from the engine ECU; (4) SNMP — enables integration with network management systems and data center infrastructure management (DCIM); (5) SMS/GSM — 4G modem option for SMS alarm notifications and basic remote monitoring via phone. Most controllers can be configured to send SMS on alarm, start, stop, and scheduled status updates; (6) USB — local configuration and data download via PC software; (7) Proprietary cloud platforms — DSE (DSEWebNet), ComAp (WebSupervisor), Datakom (Rainbow Plus). Allow real-time monitoring, historical trending, and remote control from any web browser. HUAQUAN can supply controllers pre-configured with your required communication module.

Firmware update procedure: (1) Download the latest firmware from the controller manufacturer's website — ensure it matches your exact controller model and hardware revision. Loading the wrong firmware can brick the controller; (2) Back up the existing configuration file before updating — the firmware update may reset all settings to default; (3) Connect the controller to a PC via USB or RS232. Ensure a stable power supply — loss of power during an update can corrupt the controller's memory; (4) Use the manufacturer's configuration software (DSE Configuration Suite, ComAp PC Suite, Datakom Rainbow, SmartGen Link) to initiate the update. Follow the on-screen instructions exactly. Do not disconnect or power cycle during the update process (typically 2-5 minutes); (5) After the update, reload your saved configuration file. Verify all settings: voltage, frequency, engine protections, input/output configuration; (6) Test ALL functions: manual start, auto start (simulate mains failure), alarm testing (test oil pressure and temperature inputs), load transfer, and remote communication. Never assume a firmware update 'just works' — a single misconfigured parameter can prevent the generator from starting during a real outage. Keep firmware reasonably current — manufacturers release updates to fix bugs, add features, and address security vulnerabilities.

The Magnetic Pickup (MPU) is a sensor that detects engine speed by generating an AC voltage pulse each time a gear tooth passes its magnetic tip. The controller counts these pulses to determine RPM — this is the primary speed signal. Without a working MPU, the controller cannot: initiate fuel delivery, detect overspeed, or display RPM. Gap setting procedure: (1) Rotate the engine manually until a flywheel ring gear tooth is directly under the MPU mounting hole; (2) Thread the MPU in by hand until it gently touches the tooth — DO NOT force it; (3) Back the MPU out 3/4 to 1 turn (approximately 0.5-0.8mm or 0.020-0.030 inch gap). This is the standard setting for most generators; (4) Lock the jam nut while holding the MPU to prevent it from turning; (5) Verify output: crank the engine and measure AC voltage at the MPU leads at the controller. Minimum: 2-5V AC during cranking, 10-30V AC at rated speed. If voltage is too low, the controller won't detect the signal — reduce the gap slightly (1/8 turn in). If the MPU physically hits the ring gear, the gap was too tight — back it out. A damaged MPU tip can't generate a clean signal.

Current Transformers (CTs) step down the generator's output current (hundreds of amps) to a low current (typically 5A or 1A) that the controller can measure. Wiring rules: (1) Phase correspondence — CT on Phase A (U) connects to the controller's Phase A CT input. Mismatched CTs give incorrect power and power factor readings; (2) Polarity — CTs have a polarity marking (P1/K toward the source, P2/L toward the load or vice versa depending on standard). The secondary S1 and S2 must connect to the controller with correct polarity. Reversed CT gives negative kW readings; (3) NEVER open-circuit a CT secondary while the generator is running and loaded — the CT will generate dangerously high voltage (thousands of volts) that can destroy the CT, damage the controller, and cause electric shock. Always short the CT secondary before disconnecting the controller; (4) CT ratio — select CTs that produce 5A secondary at the generator's maximum current. A 500kW 400V generator produces 902A at full load. Use 1,000:5 CTs (secondary current at full load = 4.5A, well within the controller's 5A input); (5) CT wiring should be separate from power cables (minimum 300mm separation) to avoid magnetic interference; (6) Use twisted-pair wire for CT secondary connections to reject electrical noise. HUAQUAN can supply correctly sized CTs with mounting hardware for every generator configuration.

Common controller alarm categories: Warnings (generator continues running) — 'High Coolant Temperature Pre-alarm', 'Low Fuel Level', 'Battery Under Voltage', 'Maintenance Due'. These alert the operator but don't stop the generator. Electrical Trips (generator stops but allows restart) — 'Over Current', 'Earth Fault', 'Under/Over Voltage', 'Under/Over Frequency'. These protect the alternator and load from electrical faults. They typically self-reset and allow restart if the condition clears. Shutdown Alarms (generator stops and locks out) — 'Low Oil Pressure', 'High Coolant Temperature', 'Overspeed', 'Underspeed', 'Fail to Start', 'Emergency Stop'. These indicate conditions that could cause catastrophic engine damage. The controller locks out and requires manual reset after the fault is corrected. Never repeatedly reset and restart after a shutdown alarm without investigating the root cause. Modern controllers store the alarm with a timestamp, engine hours, and snapshot of all parameters at the moment of the alarm — use this data for diagnosis.

Yes, most modern controllers support remote monitoring upgrades: (1) GSM/4G Modem Module — connects to the controller's RS232/RS485/USB port and sends SMS alarms and status updates. Simple, low-cost, works anywhere with cellular coverage. Monthly data cost: minimal (a few MB per month); (2) Ethernet Module — connects the controller to the local network for web-based monitoring via the manufacturer's PC software or built-in web server. Requires network infrastructure and a static IP or DDNS; (3) Cloud Gateway — dedicated IoT device that connects the controller to the manufacturer's cloud platform (DSEWebNet, WebSupervisor, etc.) via cellular or Ethernet; (4) Third-party RTU/PLC — Modbus RTU or TCP connection to a building management system (BMS) or SCADA. More integration work but allows centralized monitoring of multiple generators alongside other building systems; (5) For older controllers without communication ports, retrofit with a universal GSM auto-start module or upgrade the controller entirely. HUAQUAN can recommend the appropriate monitoring solution for your specific controller model and provide all hardware and configuration support.

Controller protection testing (should be done annually): (1) Low Oil Pressure — start the generator and disconnect the oil pressure sender/sensor wire. The controller should alarm and shut down within the programmed delay. Reconnect and reset; (2) High Coolant Temperature — use a potentiometer in place of the temperature sender to simulate high temperature, or disable the sender (open circuit simulates infinite temperature on many controllers). Verify shutdown within programmed delay; (3) Overspeed — adjust the overspeed setpoint temporarily to a value BELOW the current operating speed (e.g., set to 1,400 RPM for a 1,500 RPM set). The controller should trip immediately. Return to original setting; (4) Emergency Stop — press the emergency stop button. Engine must stop immediately and the controller must show Emergency Stop alarm. Reset the button and controller; (5) Underspeed — adjust the underspeed setpoint above the operating speed temporarily to test; (6) Overcurrent — apply a test load (load bank) that exceeds the overcurrent setpoint. The controller should trip per the programmed delay curve. NEVER test protection functions by creating actual dangerous conditions (running without oil, overheating) — always use simulated sensor inputs or setpoint manipulation.

Maintenance timer reset procedure varies by brand but follows a general pattern: (1) DSE controllers — enter the configuration menu (PIN required, default 1234), navigate to 'Scheduler' or 'Maintenance Alarm', and reset the run-hours counter; (2) ComAp — use the PC software (InteliMonitor) and reset the 'Next Service' parameter, or enter the controller menu and clear the alarm; (3) Datakom — navigate to the service menu, enter the service password, and reset the service interval; (4) SmartGen — press and hold the 'Stop/Reset' button for 5 seconds when the maintenance alarm is displayed, or navigate to the configuration menu. Before resetting: (1) Actually perform the maintenance! The timer is tracking real engine hours. Resetting without doing the work is like resetting a check-engine light — you're disabling a critical safety system; (2) Document the maintenance: date, engine hours, work performed, parts replaced, technician name; (3) Set the NEXT service interval correctly — many controllers allow you to program a custom interval (e.g., 250 hours for oil change, 500 hours for full service). HUAQUAN provides controller configuration guides for all brands we supply.

Load shedding is the automatic disconnection of non-critical loads when the generator approaches its rated capacity, preventing overload and potential shutdown. Controller-managed load shedding: (1) The controller monitors generator kW output via CTs. When kW exceeds a programmable threshold (typically 80-85% of rated), the controller activates load-shed relay outputs to disconnect pre-designated non-critical loads (air conditioning, water heaters, non-essential lighting); (2) Multi-stage shedding: Stage 1 at 80% load — shed lowest priority loads. Stage 2 at 90% — shed medium priority. Stage 3 at 95% — shed all non-critical; (3) Hysteresis: loads are reconnected only when total load drops below 70% for a programmable period (typically 5-10 minutes), preventing hunting (cycling on/off); (4) Some controllers implement rotating load shedding — cycling the shed among multiple load groups to share the inconvenience; (5) Load shedding is configured in the controller's I/O settings and requires the facility's electrical distribution to be designed with contactor-controlled load circuits. It's far more cost-effective than oversizing the generator to cover every possible simultaneous load.

Incorrect kW/power factor readings are almost always caused by CT or voltage sensing wiring issues: (1) CT polarity reversed on one phase — the kW from that phase subtracts instead of adds, reducing the total kW reading. Check that CT P1 (source side) connects to the controller's CT+ terminal; (2) CT not matched to the correct voltage phase — CT on Phase A must connect to the controller's Phase A CT input, and the controller must sense Phase A voltage. If CT-A is wired to CT-B input while sensing voltage-A, the phase angle is 120 degrees off, giving nonsense power readings; (3) CT ratio set incorrectly in the controller — if the actual CTs are 1000:5 but the controller is configured for 500:5, all current and power readings will be double; (4) Voltage sensing wired to the wrong side of a delta-wye transformer — the phase shift introduces a 30-degree error in power calculations; (5) Load with extremely low power factor (capacitive or highly inductive) — beyond the controller's measurement range. Check for power factor correction capacitors that are over-correcting; (6) Verify readings with a calibrated handheld power quality analyzer at the same measurement point. If the handheld reads correctly and the controller doesn't, the wiring or configuration is wrong.