The La Marche Model A31 is a transistorized DC to AC inverter designed to power an AC load. It provides a sine wave output with approximately 5% total harmonic distortion into AC loads with power factors up to 0.8 over a wide DC input range. The ferroresonant output transformer provides input to output isolation, output regulation, current limiting, and filtering. The DC input from the battery source is switched by transistors in all solid-state electronic circuitry to produce a sine wave output. The DC input sources are sensed for low and high voltage conditions, and the unit automatically turns off if the DC input is not within the proper range.
Important Safety Instructions:
Before using this equipment, it is crucial to read all manuals and documents related to this inverter and any connected equipment. A copy of the inverter's manual should always be kept nearby.
Electrical Safety:
Hazardous voltages are present at the input of power systems. The output from inverters and batteries, while potentially low in voltage, can have a very high current capacity, posing a risk of severe or fatal injury. When working with any live battery or power system, always follow these precautions:
- Never work alone on a live power system; someone should always be close enough to assist.
- Remove personal metal items such as rings, bracelets, necklaces, and watches.
- Wear complete eye protection (with side shields) and clothing protection.
- Always wear gloves and use insulated hand tools.
- Lethal voltages are present within the inverter. Parts inside may remain energized even after disconnecting AC input power. Always check with a meter before proceeding and avoid touching uninsulated parts.
- Installation should be performed by a licensed electrician.
- Always disconnect the inverter from the supply, batteries, and loads before maintenance, part replacement, or cleaning.
- Always assume an electrical connection is live and check its connection relative to ground.
- Prevent liquids or wet materials from contacting internal components.
- Do not operate this inverter outside the input and output ratings listed on its nameplate.
- Do not use this inverter for purposes not described in the operation manual.
Mechanical Safety:
- The inverter or its parts may become very hot during normal operation. Exercise care when working nearby and avoid placing items on top of the inverter.
- Do not expose the equipment to rain or snow. Install it in a clean, dry location.
- Do not operate the equipment if it has received a sharp blow, been dropped, or otherwise damaged.
- Do not disassemble the inverter. Incorrect re-assembly can lead to electric shock or fire.
- If enclosure modifications (e.g., drilling for conduit) are necessary, ensure the interior is protected from metal shavings and debris. Remove any remaining debris before energizing.
Battery Safety:
Always follow the battery manufacturer's safety recommendations. DO NOT smoke or introduce sparks or open flames near a battery, as some batteries generate explosive gases.
- When removing battery connections, always remove the grounded terminal first.
- Remove personal metal items.
- Wear rubber gloves, safety glasses, and a rubber-lined vest/apron when working near a battery.
- Have plenty of fresh water and soap nearby for electrolyte contact.
- If electrolyte contacts skin or clothing, wash immediately with soap and water.
- If electrolyte enters the eye, immediately flood the eye with running cold water for at least ten minutes and seek medical attention.
- Do not drop or place materials on a battery, as a spark or short-circuit could cause an explosion.
Inverter Location:
- Allow at least 6 inches of free air on all vented surfaces for proper cooling.
- Ensure sufficient clearance to open the front panel for servicing.
- Do not operate this inverter in a closed-in area or restrict ventilation.
- Do not place the inverter below the battery.
- Never allow battery electrolyte to drip on the inverter when reading specific gravity or filling the battery.
- Do not place the inverter directly above a standard flooded battery, as gases can corrode and damage equipment.
- A sealed maintenance-free or valve-regulated lead-acid (VRLA) battery may be placed below this equipment.
Check for Damages:
Before unpacking, note any damage to the shipping container and take pictures. Inspect the product's exterior and interior for damage. If damage is observed, take pictures and contact the carrier immediately to file a claim. Contact La Marche for a Return Material Authorization number for evaluation and repair. Failure to properly file a claim or provide a copy of the claim may void warranty service for physical damages.
Returns for Service:
Save the original shipping container. If the product needs service, it should be packaged in its original container. If the original container is damaged/unavailable, ensure the product is packed with at least three inches of shock-absorbing material. La Marche is not responsible for damage caused by improper packaging.
Inspection Checklist:
- Enclosure exterior and interior are not marred or dented.
- No visibly damaged components.
- All internal components are secure.
- Printed circuit boards are firmly seated.
- All hardware and connections are tight.
- All wire terminations are secure.
- All items on the packing list are included.
Handling:
Equipment can be very heavy with uneven weight distribution. Use adequate manpower or equipment for handling. Until securely mounted, care must be taken to prevent accidental tipping or dropping.
Technical Specifications (A31):
- DC Input Voltages:
- 24VDC: 21 - 30VDC
- 48VDC: 42 - 60VDC
- 120VDC: 105 - 150VDC
- Voltage Range: ± 10% from nominal
- AC Output:
- Voltage: 1 Phase – 120VAC (Standard), 208VAC, 220VAC, 240VAC
- Power: 1000VA – 15000VA (0.8 lagging factor)
- Regulation:
- Line Regulation: ±3% over DC battery range
- Load Regulation: ±4% from no load to full load
- Frequency Regulation: ±0.5% (Quartz Clock)
- Approximate Efficiency:
- 24VDC: 70-75%
- 48VDC: 85-90%
- 120VDC: 85-90%
- Total Harmonic Distortion: Approximately 5% at nominal DC input & full load. Less than 3% for any single harmonic.
- Meters:
- Options 06C/06D – Analog DC Ammeter & DC Voltmeter ± 2% Accuracy
- Option 22D - Digital DC Ammeter & DC Voltmeter ± 1% Accuracy
- Protection:
- Current Limit: Approximately 150%, protected by AC Output Breaker
- Input: DC Breaker, Reverse Polarity Protection Indicator, Filter Pre-Charge Circuit
- Output: AC Breaker, AC Bypass Line Fuse
- Environmental:
- Audible Noise: Less than 65dBA at any point 5 feet from any vertical surface
- Operating Temperature: 32 to 122°F (0 to 50°C)
- Storage Temperature: -40 to 140°F (-40 to 60°C)
- Relative Humidity: 0 to 95% (non-condensing)
- Cooling: Convection Cooled (4000VA and larger inverters are fan-assisted)
- Shock: Withstands shock developed when one edge of the container is dropped six inches while the opposite edge is resting on the ground, or it is dropped two inches without any physical damage or degradation of electrical performance.
- Vibration: Withstands vibration encountered in shipping without physical damage or degradation of electrical performance.
- Altitude: Capable of operation at altitudes up to 3,300 feet at an ambient temperature of up to +50°C (122°F) and 10,000 feet at an ambient temperature of up to +40°C (104°F).
- Ventilation: Mount so ventilating openings are not blocked and air entering the cabinet does not exceed 50° C (122°F).
Usage Features:
- Model Number Understanding: The A31 model number is coded to describe its features. The nomenclature nameplate on the inverter provides the model number, which can be used with the provided chart to determine the configuration (Volt-Amp Rating, Input DC Volts, AC Voltage Codes, Battery Cell Type, Frequency Code, Factory Assigned Accessory Code).
- Installation:
- Storing the A31: If stored for more than a few days, keep it in its shipping container within an ambient temperature of -40 to 140°F (-40 to 60°C) with 0-95% non-condensing relative humidity. Storage should not exceed 2 years due to the limited shelf life of DC filtering capacitors.
- Moving the A31: After inspection, identify the enclosure style and weight using the provided table (Table 1 - Case Type and Weight Table).
- Mounting the A31: Consider the size and weight. The rack and/or floor must support the inverter's weight plus a safety factor. Refer to the data sheet for weight and mounting method. Location should be 32°F to 122°F (0°C to 50°C) with non-condensing relative humidity no higher than 95%, free of explosive materials and liquids. Convection cooling requires at least 6 inches (152 mm) of free air on top, bottom, left, and right sides. Maintain 36 inches (914 mm) or more clearance at the front for operation and maintenance. Use machine bolts with flat washers, lock washers, and nuts for vibration-free, corrosion-resistant mounting.
- Rack-Mounting: The 9D, 9E, 33, and 39 enclosures are shipped with necessary brackets for rear mounting on a relay rack. The 39 enclosure supports 19" or 23" racks, while 9D, 9E, and 33 enclosures support 23" racks. Ensure conduit entrances and knockouts are accessible after mounting, and provide at least 6 inches (152mm) of air space above and below for cooling.
- Floor-Mounting: Standard for 70, 72, 44, and 47B enclosures. Install four anchor bolts, place the inverter, add mounting hardware, and tighten securely. Refer to Figure 4 for hardware specifications and dimensions.
- DC Input Connections: Before working inside, ensure all incoming AC/DC power is de-energized and/or isolated. Verify no voltage with a voltmeter. Confirm the inverter matches the battery cell number and type specified on the nameplate. Select wire size using Table 4 (AC/DC & Ground Wire Size Minimum Requirements), based on 110-115% of the input current. Feeder breaker should match the DC protection size in the inverter. Ensure AC/DC breakers and Inverter ON/OFF switch are OFF. Check DC input cable polarity with a multimeter (positive to POS, negative to NEG). A battery disconnect breaker between the inverter and battery bank is recommended.
- AC Output/AC Bypass Line Connections: A terminal strip is provided for AC load and AC bypass line. Before working inside, ensure all incoming AC/DC power is de-energized and/or isolated. Verify no voltage with a voltmeter. Select wire size using Table 4. Connect an earth ground lead to the terminal marked ground and to the LINE SYNC INPUT (GND) terminal. For AC load, connect phase (hot) to LOAD (Ø) and neutral to LOAD (N). For AC bypass line, connect phase (hot) to LINE SYNC INPUT (Ø) and neutral to LINE SYNC INPUT (N). For inverters with static switch option (22P, 22S, 164, or 165), also connect AC bypass line phase (hot) to LINE (Ø) and neutral to LINE (N).
- Operation:
- A31 Start-Up: All equipment is factory-inspected and adjusted to default values. Do not make adjustments unless the equipment has been energized and settings are incorrect.
- Checking the Installation: Before start-up, verify all connections are correct and tightened securely. Check for loose connections or unsecured components. Verify AC bypass line and battery/load voltage match the inverter nameplate.
- Start-Up Sequence: Determine if the inverter has the static switch option (22P, 22S, 164, or 165) by referring to the manual's front page, then follow the appropriate instructions.
- For Standard Inverters (No Static Switch):
Push and hold Pre-Charge button until green READY LED illuminates.
Release Pre-Charge button, immediately turn on DC breaker, then turn inverter ON/OFF switch (SW-1) to ON. Inverter should hum.
Turn on AC breaker.
Measure output voltage across AC LOAD terminals to confirm it matches nameplate.
- For Inverters with 1ms Static Switch (Option 22P/22S):
Push and hold Pre-Charge button until green READY LED illuminates.
Release Pre-Charge button, immediately turn on DC breaker, then turn inverter ON/OFF switch (SW-1) to ON. Inverter should hum.
Turn on AC breaker. Front panel LEDs will perform a lamp test. After test, Inverter Available LED should be lit. For 22P, Preferred Source LED should also be lit. For 22S, Alternate Source LED should also be lit.
Turn on AC bypass source (utility). After a few seconds, Phase Lock and Utility Available LEDs should also be on. Ensure inverter is set to Auto Retransfer. For 22S, Preferred Source LED should also turn on and Alternate Source LED turn off.
Measure output voltage across AC LOAD terminals to confirm it matches nameplate.
- For Inverters with 10-15ms Static Switch (Option 164/165):
Push and hold Pre-Charge button until green READY LED illuminates.
Release Pre-Charge button, immediately turn on DC breaker, then turn inverter ON/OFF switch (SW-1) to ON. Inverter should hum.
- Inverter Prime (Option 164):
A. Turn on AC breaker. LOAD ON PRIME and PRIME AVAIL. LEDs on 139A static switch board should be lit. Green INVERTER AVAILABLE LED on front panel should be lit.
B. Turn on AC bypass source (utility). Yellow BYPASS AVAILABLE LED should also be lit.
C. Measure output voltage across AC LOAD terminals to confirm it matches nameplate.
- Inverter Standby (Option 165):
A. Turn on AC breaker. LOAD ON PRIME and PRIME AVAIL. LEDs on 139A static switch board should be lit. Green INVERTER AVAILABLE and red LOAD ON ALTERNATE LED on front panel should be lit.
B. Turn on AC bypass source (utility). Yellow BYPASS AVAILABLE LED should also be lit. LOAD ON ALTERNATE LED should be off after a few seconds.
C. Measure output voltage across AC LOAD terminals to confirm it matches nameplate.
* CAUTION: Before resetting the DC breaker, pre-charge instructions must be followed to prevent damage.
* NOTE: If green READY LED does not light, check battery type and cell count. If red REVERSE POLARITY LED illuminates, battery is installed incorrectly; disconnect wires immediately to prevent damage.
- LED Indicators (S2A-167S Oscillator/Line Sync Board): This board provides voltage sensing, oscillator circuits, low/high DC input voltage protection, and ensures inverter output syncs with AC bypass line. It has 3 red status LEDs:
- Phase Lock (PL): Turns on if inverter output is in sync with AC bypass line.
- High DC Voltage (HV): Turns on and inhibits inverter output if DC input voltage exceeds threshold. Turns off when high DC voltage condition is no longer present.
- Low DC Voltage (LV): Turns on and inhibits inverter output if DC input voltage falls below threshold. Turns off when low DC voltage condition is no longer present, and inverter output resumes.
- Factory Settings: All A31 inverters are factory-set based on the model number:
- Low DC Voltage Shutdown: 1.73 V/C for LA, 1.10 V/C for NC
- High DC Voltage Shutdown: 2.45 V/C for LA, 1.60 V/C for NC
- Phase Lock Frequency Range: 57.5 Hz - 62.5 Hz
- Current Limit: 150% of nominal output current (fixed; not adjustable)
- NOTE: V/C – Volts per Cell, LA – Lead Acid, NC – Nickel Cadmium, Hz – Hertz.
Maintenance Features:
All work inside the A31 inverter must be performed by qualified personnel. La Marche is not responsible for damages caused by unqualified technicians. Before working inside, ensure AC power is off at the main breaker box and battery is disconnected from DC input terminals. Verify no voltage with a voltmeter.
- Performing Routine Maintenance: Minimal maintenance is required, but routine checks and adjustments are recommended for optimum system performance.
- Yearly:
- Confirm air vents are open. Remove dust and debris from inverter interior.
- Verify all connections are tight.
- Perform a visual inspection on all internal components.
- Check front panel meters for accuracy and LED operation.
- Check capacitors for electrolyte leakage and replace if necessary.
- Every 7 Years: If operated consistently in extreme temperatures, capacitors should be replaced.
- Every 10 Years:
- Check magnetics, components, and wiring for signs of excessive heat.
- Replace capacitors if not done at the 7-year interval.
- Troubleshooting Procedure: Troubleshooting should only be performed by trained service personnel or experienced electricians. Before complicated testing, inspect the inverter using the guide:
- Check AC output cables, connections, battery type, and number of cells against inverter rating.
- Check input connections, input voltage, and breaker size.
- Check for shipping damage, loose connections, broken wires.
- Check DC input cables for proper polarity and security. DC voltage input must be above 1.73 volts per cell (lead acid) and 1.1 volts per cell (nickel cadmium).
- Check AC bypass line connections for proper security. Total load must not exceed nameplate rating.
- Ensure batteries and loads are free from defects, as they can cause failures.
- NOTE: If the problem is in printed circuit boards, replace the board. Do not attempt field repair.
- La Marche Service Technicians are available for troubleshooting or scheduling service. When calling, provide:
- Equipment model number and serial number.
- Measured DC input voltage and AC bypass voltage (if applicable).
- Measured AC output voltage, with and without loads.
- Result of AC and DC breaker checks.
- AC output current and voltage with load connected.
- NOTE: When ordering replacement parts, drawings, or schematics, provide model number, serial number, and problem description.
- La Marche Phone Number: (847) 299-1188
- 24-hour Emergency Number: (847) 296-8939
- Troubleshooting Chart: (Isolate from all power sources before interior verifications or part replacements.)
- Symptom: Inverter AC Breaker Trips
- Possible Cause: Overload Condition, Shorted Equipment or Component on AC output, Defective AC Breaker, Shorted SCRs (if applicable).
- Symptom: Inverter DC Breaker Trips
- Possible Cause: Capacitor Pre-Charge Circuitry Improperly Used, Defective C1, C2, or C4 Capacitor, Defective S2A-167S Oscillator/Line Sync Board, Defective S2A-297/S2A-306 IGBT Drive Board, Defective IGBT Module, Shorted Wiring, Incorrect Battery Connected, Shorted Battery Cells.
- Symptom: Lockout (No AC Output)
- Possible Cause: Low or No DC Voltage Input, Defective Inverter AC Breaker, Defective Inverter DC Breaker, Broken Wire, Shorted or Open C1 Capacitor, Low or High DC Voltage Shutdown Activated or Improperly Set, Open F2 Fuse, Open Fuse on S2A-297/S2A-306 IGBT Drive Board.
- Symptom: F2 Fuse Clears
- Possible Cause: Defective S2A-167S Oscillator/Line Sync. Board, Defective S2A-297/S2A-306 IGBT Drive Board.
- Symptom: Bypass AC Breaker Tripped
- Possible Cause: AC Bypass Line Overload Condition, Shorted SCRs (if applicable).
- Symptom: READY LED for Pre-Charge Circuitry Not Illuminating
- Possible Cause: Defective C2 Capacitor, Defective READY LED, Improper Connection to S2A-172 Reverse Polarity Board, No or Low DC Voltage Input, Inverter ON/OFF Switch set to ON, Defective IGBT Module, Defective C4 Capacitor, Open Pre-Charge Resistor, Defective Batteries.
- Symptom: Inverter's AC Load Supplied by Wrong Source
- Possible Cause: Defective SCR Module, Defective Static Switch, Overloaded Prime Source.
- Ordering Replacement Parts: Contact La Marche with the model and serial number of the battery inverter, parts needed, and quantity.
- SCR Modules: Disconnect wiring. Use ohmmeter: three main terminals (A1K2, K1, A2) should read high resistance in both directions. Gate (G1) should read high resistance between top (A1K2), bottom (A2) terminals and low resistance (10-40 Ohm) to middle (K1) terminal. Gate (G2) should read high resistance between middle (K1) and (A2) terminal and low resistance between terminal (A1K2). (Wiring diagram on component side).
- IGBT Modules: Use ohmmeter: resistance between Terminal 1 (collector) and Terminal 2 (emitter) should read low resistance with negative lead on Terminal 1, high resistance when leads are reversed. With negative lead on one, measure to Terminal 3 (high resistance). With negative lead on Terminal 1, measure to Terminal 5 (low resistance). When S2A-297 or S2A-306 card is removed, jump gate and emitter of IGBT with copper wire to protect from ESD damage.
- C1, Resonating Capacitors 560 VAC – 660 VAC: With ohmmeter, meter should deflect to low resistance, then gradually rise to high resistance.
Manufacturer's Standard Warranty:
All La Marche equipment is warranted to be free from defects in workmanship and material for one year from purchase. Magnetics and power diodes are warranted on a parts replacement basis for nine additional years under normal use (total 10 years). During the first year, defective parts are replaced without charge if due to faulty material or workmanship (not tampering, abuse, misapplication, or improper installation). For the remaining nine years, the warranty covers parts replacement only; no labor or other services are provided.
- Component Replacement/Repair:
- Purchaser requests replacement part(s): Contact Factory for return authorization and purchase order. Part(s) shipped and invoiced. Credit issued after defective part(s) are returned and inspected.
- Equipment returned to Factory: Customer obtains authorization. If defect is due to faulty material/workmanship, repairs are free during the first year. For Extended Warranty, parts are free, but labor costs apply (purchase order required for labor). Transportation charges/duties borne by Purchaser.
- Factory service representative at equipment location: La Marche's field service labor rates apply (purchase order required for labor and transportation).
- Purchaser assumes full responsibility for proper installation, adjustments, and service arrangements. Minor adjustments: contact local La Marche sales representative.
- All sales are final. Only standard La Marche inverters are returnable (25% restocking fee). Special inverters are not returnable.
- La Marche Manufacturing Co. is not liable for consequential damages, loss, or expense from product use or inability to use. Alterations by unauthorized persons void warranty.
- La Marche reserves the right to revise equipment production without obligation to incorporate revisions in earlier models.
- Failure to object to purchase order provisions does not waive terms or conditions.
- THE ABOVE WARRANTY IS EXCLUSIVE, SUPERSEDES AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS. NO PERSON, AGENT, OR DEALER IS AUTHORIZED TO GIVE ANY WARRANTIES ON BEHALF OF THE MANUFACTURER, OR TO ASSUME FOR THE MANUFACTURER ANY OTHER LIABILITY IN CONNECTION WITH ANY OF ITS PRODUCTS UNLESS MADE IN WRITING AND SIGNED BY AN OFFICIAL OF THE MANUFACTURER.
Manufacturer's Extended Parts Warranty:
(This warranty applies if the Extended Parts Warranty is purchased or if purchased within the first 12 months after invoice date).
All La Marche equipment is warranted to be free from defects in workmanship and material for one year from invoice date. Any defective part (except protective devices, d.c. connectors, wear-related items) within the first year is replaced without charge if due to faulty material or workmanship (not tampering, abuse, misapplication, or improper installation). Labor and parts are covered during this one-year period.
- Additional Four Years (Parts Replacement Only): For the next four years after the one-year warranty, any defective part (except protective devices, d.c. connectors, wear-related items) is replaced if due to faulty material or workmanship (not tampering, abuse, misapplication, or improper installation). This period covers parts replacement only; no labor or other services are provided. If equipment is returned to the factory (freight prepaid), parts and labor are covered.
- Magnetics and Power Diodes (10-Year Warranty): Warranted for ten years from invoice date if defect is due to faulty material or workmanship (not tampering, abuse, misapplication, or improper installation). Labor and replacement magnetics and power diodes are covered under the extended warranty during the initial five-year period. For the next five years, the warranty covers parts replacement only; no labor or other services are provided.
- Component Replacement/Repair during Extended Warranty:
- Purchaser requests replacement part(s): Contact Factory for return authorization and purchase order. Part(s) shipped and invoiced. Credit issued after defective part(s) are returned and inspected.
- Equipment returned to Factory: Customer obtains authorization. If defect is due to faulty material/workmanship, all repairs are free under the Extended Warranty. Transportation charges/duties borne by Purchaser.
- Factory service representative at equipment location: La Marche's field service labor rates apply (purchase order required for labor and transportation).
- Purchaser assumes full responsibility for proper installation, adjustments, and service arrangements. Minor adjustments: contact local La Marche sales representative.
- All sales are final. Only standard La Marche units are returnable (25% restocking fee). Special units are not returnable.
- La Marche Manufacturing Co. is not liable for consequential damages, loss, or expense from product use or inability to use. Alterations by unauthorized persons void warranty.
- La Marche reserves the right to revise equipment production without obligation to incorporate revisions in earlier models.
- Failure to object to purchase order provisions does not waive terms or conditions.
- THE ABOVE WARRANTY IS EXCLUSIVE, SUPERSEDES AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS. NO PERSON, AGENT OR DEALER IS AUTHORIZED TO GIVE ANY WARRANTIES ON BEHALF OF THE MANUFACTURER, OR TO ASSUME FOR THE MANUFACTURER ANY OTHER LIABILITY IN CONNECTION WITH ANY OF ITS PRODUCTS UNLESS MADE IN WRITING AND SIGNED BY AN OFFICIAL OF THE MANUFACTURER.
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