ESD5221 speed controller Overview The ESD5221 speed controller provides a cost effective replacement for imported controllers while maintaining reliability and performance. It works with a wide range of engines and actuators and features improved circuitry for enhanced stability. Every unit undergoes a 100 percent factory thermoelectric aging test to ensure consistent quality. Key benefits Replacement for imported controllers without sacrificing performance or reliability. Broad compatibility with many engine types and speed sensors, simplifying installation and inventory. Improved circuit design for higher stability and better dynamic response under changing loads. Produced using imported spare parts for consistent component quality. Factory aging test ensures long term reliability and reduces initial failure risk. Main functions and attributes Model: ESD5221 speed controller. Speed stability: better than plus/minus 0.25 percent. Speed range: 1 kHz to 7.5 kHz. Thermal stability: maximum plus/minus 1 percent. Idle adjustment: 160 Hz plus/minus 20 Hz to 95 percent of rated speed. Droop adjustment: minimum position 15 Hz plus/minus 6 Hz per ampere of load current change; maximum position 400 Hz plus/minus 75 Hz per ampere of load current change. External speed adjustment: plus/minus 200 Hz using an external 1 k ohm potentiometer. AUX input sensitivity: 148 Hz per 1 V input, plus/minus 10 Hz. Impedance: 1 M ohm. Start fuel adjustment: 160 Hz plus/minus 20 Hz to 70 percent of rated speed. Ramp time adjustment: 1.5 to 20 seconds. 10 V output: maximum 20 mA. Actuator continuous current: minimum 2.5 A, maximum 10 A. Speed sensor input range: 0.5 to 120 RMS. Power supply: compatible with 12 V and 24 V DC battery systems. Grounding polarity: negative. Power consumption: 50 mA. Size: approximately 15.2 x 16.5 cm (6 x 6.5 in). Environmental and mechanical limits: operating temperature minus 40 degrees Celsius to 85 degrees Celsius; storage temperature minus 55 degrees Celsius to 90 degrees Celsius; operating humidity up to 95 percent; vibration 20 to 100 Hz at 500 mm/s. Important note: performance parameters are measured at a working frequency of 4000 Hz. Package contents 1 x speed controller 1 x user manual Practical applications and typical scenarios Standby and prime power generator sets: maintain steady engine speed under varying electrical loads to protect sensitive equipment and improve generator output stability. Marine and industrial engines: provide reliable speed control for propulsion engines, pumps, and compressors where consistent RPM and rapid response to load changes are required. Agricultural and construction equipment: control engine speed for irrigation pumps, mobile power units, and other off road machinery that require robust, field proven controllers. Why choose this controller The ESD5221 combines widespread compatibility, a stable and improved control circuit, and factory verified aging tests to offer a dependable alternative to higher cost imported controllers. Its adjustable parameters allow fine tuning for specific engine and application requirements while operating across common 12 V and 24 V electrical systems.