Answer: Good! On almost inverters over 1000 watts, the fans are connected to a thermal switch which will only allow the fans to come on when they reach a certain temperature. This helps keep your batteries holding their charge longer, and also makes it QUIET! Hooray!
Question #2: Power tools and microwave ovens won’t start
Answer: Read the information panel on each power tool carefully to accurately determine the tool’s input wattage. Please remember that the power needed to start the power tool may be as much as 2 to 6 times its continuous wattage requirements.
Question #3 : “Buzzing” sound in audio systems
Answer: Some inexpensive stereo systems and “boom boxes” emit a buzzing sound from their speakers when operated from the power inverter. This occurs because the power supply in the electronic device does not adequately filter the modified sine wave produced by the inverter. The only solution to this problem is to use a higher quality sound system that incorporates a higher quality power amplifier supply.
Question #4: Television interference problem
Answer: The inverter is shielded to minimize interference with TV signals. The problem may not be with the inverter. However, in some instances, some interference may still be visible, particularly with weak TV signals. Try the following corrective measures:
- Position the inverter as far as possible from the television, the antenna and the antenna cables. Use an extension cable, if necessary.
- Adjust the orientation of the inverter, the antenna cables and the TV power cord to minimize interference.
- Make sure that the antenna feeding the television provides an adequate (“snow free”) signal and that high quality, shielded antenna cable is used.
- Do not operate high-power appliances or tools when you are watching TV.
Question #5: Using A Polarity Tester with An Inverter"When I check the 120 volt output of an inverter with a three light polarity tester, all three lights come on. There is no fault description for the tester covering this. My ground fault outlets do not trip. Is there a problem?"
Answer : No. What you are seeing is normal if you are testing the output of a Modified Sine Wave (MSW) inverter. The device you’re using is for use with household utility power; the internal wiring of the inverter causes this symptom.
Question #6: Voltage Measurement Issues (AC Output)
"I've installed the modified sine wave inverter and it's working okay. However, the output voltage doesn't seem right. There is 124 vac between the hot and neutral pins but the safety ground is not at 0 volts with respect to the neutral pin. Instead, the safety ground appears to float about halfway between the neutral and hot pin voltage. Please explain what's going on!"
Answer: Your inverter is designed to have loads plugged directly into it and not be permanently connected to an AC distribution system. The fact that the inverter is not a permanent installation means the US NEC (United States National Electrical Code) doesn't apply, and the NEC is the main place where the requirement resides for single-phase 120Vac or 240Vac systems to have neutral bonded to earth. The US standard for inverters of this sort, UL458, does not have a requirement for a bonded neutral on the output of inverters.
Regarding the voltage that the you are measuring, the ground does not float halfway, rather the neutral is not at 0 volts. The grounding is correct, in that loads plugged in will have their chassis held at the same ground potential as the chassis of the inverter, but the neutral has approximately 60V on it instead of the usual 0V. The impact of that is minimal, since wiring and equipment connected to the neutral side of the circuit are required by safety standards to be treated as if they were at 120Vac. This is because there are many receptacles that are wired backwards or 2-prong plugs that are not polarized. As a result the 60V neutral is not accessible to the user, and any shock hazard presented is mitigated by lack of access.
The main safety agencies, CSA, UL, and ETL, have all approved inverters with this half-voltage on the neutral scheme, and the manuals contain warnings not to AC hardwire any of these inverters.
*Appliance Cautions (for Modified Sine Wave Inverters)
-DO NOT plug small appliances into the inverter AC receptacles to directly recharge their nickel-cadmium batteries. Always use the recharger provided with that appliance.
-DO NOT plug in battery chargers for cordless power tools if the charger carries a warning that dangerous voltages are present at the battery terminals.
-Not all fluorescent lamps operate properly with a modified sine wave inverter. If the bulb appears to be too bright, or fails to light, do not use the lamp with the inverter.
-Some fans with synchronous motors may slightly increase in speed (RPM) when powered by a modified sine wave inverter. This is not harmful to the fan or to the inverter.
-Certain rechargers for small nickel-cadmium batteries can be damaged if plugged into a modified sine wave inverter. In particular, two types of appliances are susceptible to damage:
(1) Small, battery-operated appliances such as flashlights, cordless razors and toothbrushes that can be plugged directly into an AC receptacle to recharge.
(2) Certain battery chargers for battery packs that are used in some cordless hand-tools. Chargers for these tools have a warning label stating that dangerous voltages are present at the battery terminals.
-DO NOT use a modified sine wave inverter with the above two types of equipment.
The majority of portable appliances do not have this problem. Most portable appliances use separate transformers or chargers that plug into AC receptacles to supply a low-voltage DC or AC output to the appliance. If the appliance label states that the charger or adapter produces a low-voltage DC or AC output (30 volts or less), there should be no problem powering that charger or adapter.