Product Specification 03255 

(Revision E, 12/2009) 

L‐Series 
Air/Fuel Ratio Control 

Applications 
The L-Series Air/Fuel (A/F) Ratio Control may
be used with the LC-50 family of integrated
throttles and mixers for engines between 5
and 100 kW (7 and 134 hp). The L-Series A/F
Ratio Control provides precise air/fuel ratio
control for engines using three-way catalytic
converters to reduce exhaust emissions. The
 Fully integrated
L-Series A/F with an LC-50 mixer with control and trim
standard production (stoichiometric) fuel hole valve
sizes will allow closed-loop stoichiometric
operation with gaseous fuels from low-quality  Reduced wiring
pipeline natural gas to HD-5 LPG (propane). and installation
The A/F Ratio Control and standard LC-50 time
configurations for mixer sizes 25, 30, 36, 43,
and 50 will accommodate the full range of fuel  Compatible with
types and fuel qualities.
natural gas or
Description  propane or both
 Does not use
This control is a microprocessor-based air/fuel ratio control for four-stroke, gaseous-fueled
engines operating with a near-stoichiometric air/fuel ratio. It is designed to work in conjunction vacuum hoses
with a three-way catalytic converter to efficiently reduce exhaust emissions. By automatically
maintaining an optimum air/fuel mixture, emissions compliance is achieved and catalyst life is  Easy setup and
maximized without operator supervision. tuning using PC-
A catalyst that simultaneously eliminates hydrocarbons (HC), carbon monoxide (CO), and based service tool
oxides of nitrogen (NOx) is referred to as a “three-way” catalyst. The use of a three-way
catalyst will reduce the emissions of a stoichiometric engine. However, for these reductions to  Tamper resistant
be reliable and maximized, and to protect the catalyst element from premature aging or
damage, a very precisely controlled air/fuel ratio is required.  Discrete output for
fault indication
The heated exhaust gas oxygen sensor (HEGO) will generate a voltage signal that is
characteristic of this ideal stoichiometric window. The HEGO sensor operates as a reference-  Voltage output for
gas sensor, and compares the residual oxygen in the exhaust gas with the oxygen in the
reference atmosphere (air circulating inside the sensor). The active sensor ceramic is heated position indication
by the internal heating element. Sensor heating reduces the influence of the exhaust gas
temperature on the sensor-ceramic temperature and therefore the temperature-dependent  Configurable I/O
sensor functions. The L-Series A/F Ratio Control monitors the system HEGO output and
adjusts fuel flow for optimum emissions.
System features include:
 Pre-catalyst, closed-loop, exhaust oxygen feedback control
 Compatible with wide range of fuel qualities: 850 BTU/SCF (34.0 MJ/m³) to 2325 BTU/SCF (93 MJ/m³)
 “On-the-fly switchable” between two sets of control targets and position limits for bi-fuel operation
 Manually switchable to enable open-loop operation
 LED/Alarm driver to indicate diagnostic states
 Programmable diagnostics including minimum and maximum positions and O2 sensor voltage
 Configurable fault and security settings
 0–5 V output for shaft position indication
 Setpoint and open-loop position adjustment using Raise/Lower or Target 1/Target 2 commands
 Bias input with programmable curve for feed-forward position and alternate open-loop position setting
Technical Manual 26251
 Woodward 03255 p.2
Flexible design. More intelligent engine control. Streamlines production process.
Specifications
Power Supply 12/24 volt system, 10 to 32 Vdc Dimensions (WxHxL) 75.7 x 88.4 x 111.3 mm
Power Consumption Reverse polarity protection, 32 W max (2.98 x 3.48 x 4.38 in.), excluding valve
Torque Nominal: 0.34 Nm (0.25 lb-ft) at 25 °C Weight 425 g (15 oz), excluding valve
Maximum Transient (at 105 °C): 0.20 Nm (0.15 lb-ft) Connector 12-pin Deutsch connector (DT06-12SA-P012)
Minimum Continuous (at 105 °C): 0.14 Nm (0.10 lb-ft) HEGO Sensor 1680-6005
Functions/Auxiliary Inputs
Function Options Position-based dynamics curve, catalyst perturbation logic, dual target setpoint/position selection, open-loop
selection, Raise/Lower setpoint selection
Programming Port Programmable with Windows GUI software (9927-1222) and harness (8923-1061)
I/O 0–5 V position indication
Discrete out for fault indication
5 aux inputs, configurable functions
Environment
Operating Temperature –40 to +105 °C (–40 to +221 °F)
Storage Temperature –40 to +125 °C (–40 to +257 °F)
EMC EN61000-6-2: Immunity for Industrial Environments
EN61000-6-4: Emissions for Industrial Environments
SAE J1113-21: Radiated Immunity (100 V/m)
SAE J1113-11: Conducted Transient Immunity – Pulse 5b, Suppressed Load Dump (45 V)
Humidity US MIL-STD 810E, Method 507.3, Procedure III
Shock MS1-40G 11 ms sawtooth
Vibration Random: 0.3 G²/Hz, 10–2000 Hz (22.1 Grms) 3 h/axis
Sine: 5 G 2.5 mm peak-to-peak, 5–2000 Hz, 3 h/axis, 90 min dwells, 1 octave/min
Thermal Shock SAE J1455, Paragraph 4.1.3.2
Fluid Resistance IP56 per EN60529
Compliance
CE Compliant with EMC Directive
89/336/EEC
Other Compliant as a component with
Machinery Directive 98/37/EC
CSA Class I, Division 2, Groups
A, B, C, D T3C
These listings are limited only to
those units bearing the CSA
agency identification.

L-Series A/F Ratio Control Outline Drawing (16 mm)

(Do not use for construction)
(also available in 22 mm, 25 mm, 30 mm, 36 mm, 43 mm, and 50 mm sizes)

For more information contact:

PO Box 1519, Fort Collins CO, USA 80522-1519
1000 East Drake Road, Fort Collins CO 80525
Tel.: +1 (970) 482-5811  Fax: +1 (970) 498-3058
www.woodward.com

Distributors & Service

Woodward has an international network of distributors and service facilities.
For your nearest representative, call the Fort Collins plant or see the
Worldwide Directory on our website.

This document is distributed for informational purposes only. It is not to be construed as

creating or becoming part of any Woodward contractual or warranty obligation unless
expressly stated in a written sales contract.
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