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ered 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” / "Leak
-
age". As this Leakage Current is diverted to earth Ground, it does not return to the electri-
cal 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.
6.1.7.1 Ground fault protection in inverter mode:
• The Grounding Sockets of the NEMA5-15R AC outlets (1, Fig 3.1) are connected to the
internal GFCI circuitry through energized condition of Ground Switching Relay K2.
• The Line and Neutral Sockets of the
NeMA5-15r AC
outlets (1, Fig 3.1) are isolated
from their Grounding Sockets. Thus, the metal chassis of the inverter and the AC
loads will also be isolated from the Line and Neutral conductors.
• The Grounding Sockets of the
NeMA5-15r AC outlets are connected to the input sec-
tion of the electronic Ground fault Protection Circuit on the power circuit board.
•
Due to the above implementation, the voltages on the Line and neutral sockets of
nema5-15r outlets (1, fig 3.1) with respect to the Grounding Sockets will be pulsing
Dc voltage with average Dc value of up to 50 vDc (will read 75 vac on the ac scale
of the voltmeter because of pulsing nature of Dc voltage). Do not touch the Line /
neutral Sockets!
• If there is a short circuit between the Line / Neutral to metal chassis in the Inverter /
load, up to 75V AC 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 nema5-15r
ac outlets 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 Ground
-
ing 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 Grid AC distribution wiring, it will see a Neutral to
Ground connection and the Inverter will trip due to activation of the Ground
Fault Protection Circuit as explained above.
6.1.8 failure to Start Some Devices on Load
Some high capacitance loads like Compact Fluorescent Lamp (
CfL) or Switched Mode
Power Supply
(SMPS)
will shut down the Inverter under overload condition if the Invert-
er is switched oN with these loads in oN condition. However, if these loads are switched
off first and switched oN only after around 10 sec after the Inverter is switched oN
(as
already recommended under switching oN procedure), the Inverter may not shut down.
Hence, do not switch oN the Inverter with such loads in oN condition.
SeCTIOn 6 |
Protections, Monitoring
& Troubleshooting
Summary of Contents for SAM Series
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