Ferroresonant Technology

Single Phase 120/208/220/240 Vac
60 or 50 Hz
1 to 15 KVA

24, 48, or 120Vdc

Oil Exploration/Gas


The LaMarche A31 Inverter is the ideal choice when AC power requirements are critical. Its ferroresonant transformer-based design and transistor switching provide an extremely reliable and high quality sine wave output (<5% THD). Applications may include the following systems: Computer, telecommunications, emergency lighting, offshore oil exploration, utility substation, security alarm, etc. The A31 has a wide range of standard features such as a sine wave output, voltage regulation, protection from AC-DC shorts, under/over-voltage conditions, input filtering and overload protection. It incorporates a DC input breaker and an automatic under/over-voltage shutdown circuit to protect the inverter. The A31 has a polarity indicator to tell you if the battery is connected incorrectly. The unit is equipped with an input filter precharge circuit, which includes an indicator to inform you that the inverter is ready for operation.

• Highly Reliable Ferroresonant Transformer 
• Available DC Inputs 24V or 48V or 120V
• DC to AC Isolation 
• Pure Sine Wave Output 
• Adjustable DC Under/Over Voltage Shutdown 
• Analog AC Ammeter & Voltmeter (2%)
• Overload/Current Limit
• Inverter On/Off Switch
• AC Circuit Breaker
• DC Circuit Breaker 
• IGBT Power Block Technology UL 1012 Listed, UL 1481 Listed (selected models) and C-UL Listed

User Manuals
Battery Ranges24 volt nominal 21-30VDC
48 volt nominal 42-60VDC
120 volt nominal 105-150VDC
InputReverse Polarity Protection IndicatorFilter Pre-charge Circuit; DC Breaker
DC Under Voltage ShutdownAdjustable
DC Over Voltage ShutdownAdjustable
AC Output Voltage120V Nominal (Standard)
240V (Optional)
208V and 220V (Optional, Not UL Listed)
Output PowerRated VA continuous for unity to .8 lagging power factor
Line Regulation±3% Over DC Battery Range
Load Regulation±4% from no load to full load
Frequency Regulation±0.5% (Quartz Clock)
Current LimitApproximately 150%. Protected by AC Output Breaker
Total Harmonic DistortionApproximately 5% at nominal DC Input and Full Load. Less than 3% for any single harmonic
NoiseLess than 32 dBrn
Audible Noise65 dB @ 5 feet
Approximate Efficiency24VDC models 70-75%
48VDC models 85-90%
120VDC models 85-90%
Load Crest FactorWill operate with Load Crest Factors up to 2.8
Operating Temperature0 to 50°C
Storage Temperature-20 to 60°C
Relative Humidity0-95% (non-condensing) Convection Cooled (3KVA and larger units may be fan assisted)
Agency ApprovalsUL 1012
UL 1481 (Available for selected models, refer to chart)

Communications21PDNP3 (RS232/RS485/Ethernet)
21QMODBUS (RS232/RS485/Ethernet)
21UDNP3 (RS232/RS485/Ethernet)
21VMODBUS (RS232/RS485/Ethernet)
High Speed Static Switch22AStatic Switch Alarm Package (For Use With 22P & 22S Only)
22DDigital Display (For Use With 22P Or 22S)
22P1ms Static Switch (Inverter Prime)
22S1ms Static Switch (Inverter Standby)
Metering06CDC Ammeter
06DDC Voltmeter
Miscellaneous123Duplex Receptacle (Not UL Listed) Consult Factory For 208 & 240VAC
130Inverter Failure Relay And Light (Not Avail w/22A)
132Inverter Failure Relay (1 Form
133Utility Available Relay (1 Form
Slow Speed Static Switch16410-15ms Static Switch (Inverter Prime)
16510-15ms Static Switch (Inverter Standby)
Standards09AUL 1481 Label (Fire Alarm) - For 48V Models Only