Samlex America SAM-3000-12 - Manual (Page 23)

20 | SAMLEX AMERICA INC. SAMLEX AMERICA INC. | 21
Low input Voltage Buzzer alarm
A buzzer alarm will sound when the voltage at the input terminals of the inverter drops
to 10.8V ± 0.3V. This is an indication that either the battery terminal voltage has dropped
due to its discharged condition and needs to be re-charged or there is an excessive volt-
age drop across the wires connecting the inverter to the battery (due to use of thinner
and longer length of wires that will produce higher voltage drop at higher loads or due
to loose connections). The user should stop operation of the electronic device at this time
since the inverter will shut down automatically shortly thereafter, when the input voltage
at the inverter further drops to 10.5V ± 0.3V. In case the alarm is due to the discharged
condition of the battery, start your engine to recharge the battery / use an appropriate
battery charger.
i
info
it is normal for the alarm to sound while the unit is being connected to or discon-
nected from the Dc power source. this is not indicative of a problem.
Ground fault protection - General
Due to loss of insulation as a result of aging of insulating materials, accident or malfunc-
tion, voltage source inside an electrical device can get connected to its metal chassis. If
the energized metal chassis is touched by a person standing on Earth Ground (considered
to be at 0V), the person will get a shock due to current leaked through the body to Earth
Ground (called Leakage Current). Such condition is called “Ground Fault”. As this Leak-
age Current is diverted to Earth Ground, it does not return to the electrical power source
supplying the AC device. Severity of electrical shock will depend upon the value of the
fault voltage on the metal chassis and the impedance in the current path to Earth Ground,
primarily the impedance of the human body (100 kΩ when dry and 1 kΩ when wet).
Human body can tolerate leakage current of up to 5mA for 15 to 30 msec.
Ground fault protection in this inverter is provided as follows:
• The Line and Neutral terminals of the AC outlet are isolated from its grounding terminal.
Thus, the metal chassis of the AC loads will also be isolated from the Line and Neutral.
• The grounding terminal of the AC outlet is connected to the input section of the Electronic
Ground Fault Protection Circuit on the power circuit board.
• Due to the above implementation, the neutral voltage will be pulsing Dc voltage with
average Dc value of up to 50VDc with respect to the metal chassis of the ac loads / metal
chassis of the inverter (will read 75 Vac on the ac scale of the Voltmeter because of puls-
ing nature of Dc Voltage). Similarly, the Line voltage will also be up to 75V with respect to
the metal chassis of the ac loads / metal chassis of the inverter . Do not touch the Line /
neutral!
• If the metal chassis of the load develops a Ground Fault condition, up to 75V will be fed to
the Electronic Ground Fault Protection Circuit and the AC output of the inverter will shut
SECTION 6 | Protections Monitoring
& Trouble-Shooting
11002-SAM-1000-1500-2000-3000-12-0814.indd 23 14-08-12 9:59 AM