22 | SAMLEX AMERICA INC.
SAMLEX AMERICA INC. | 23
i
info
it is normal for the alarm to sound while the unit is being connected to or
disconnected from the 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 unit is provided as follows (inverter is
supplying power):
• 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 50 VDc 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 pulsing 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
down.
• Ground fault protection will also operate if the neutral and ground of the ac output of the
inverter are connected (bonded) intentionally like in Service entrance / Load center for ac
distribution wiring.
!
caution!
Connecting the AC output of the unit to utility AC distribution wiring with Neutral to
Ground connection (bond) is not permitted. In AC utility distribution wiring, the Neutral
conductor is connected (bonded) to the Equipment Grounding Conductor at the Load
Center / Service entrance. both these conductors are then bonded to the earth Ground
(Ground rod). Thus, if the output of the inverter is connected to the utility AC distribution
wiring, it will see a Neutral to Ground connection and the inverter will trip due to activa-
tion of the Ground Fault Protection Circuit as explained above.
SECTION 6 |
Protections Monitoring
& Troubleshooting
Содержание SAM-1500C-12
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