PGA-016A Littelfuse Inc, PGA-016A Datasheet - Page 52

• Manufacturer Part Number: PGA-016A
• Description: BULK / WATERTIGHT COVER FOR PGR-6200 / PGR-7200
• Manufacturer: Littelfuse Inc

Specifications of PGA-016A

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

P
www.littelfuse.com/ProtectionRelays
PGN-3000
IV. RESISTANCE GROUNDING
CONVERSION
Convert Ungrounded to Resistance Grounded
Systems
Resistance grounding protects a system against transient
over-voltages caused by arcing ground faults and it provides a
method to locate ground faults. (Transient over-voltages and
inability to locate ground fault are the most common safety
issues with Ungrounded systems.)
Conversion of delta-connected or wye-connected sources
with inaccessible neutrals require a zig-zag transformer
to derive an artificial neutral for connection to the neutral
grounding resistors (NGRs). The artificial neutral is only used
for the NGR and not for distribution. During normal operation
the only current that flows in the zig-zag transformer is an
extremely small magnetizing current. When one phase is
grounded, the NGR and the zig-zag transformer provide a
path for ground-fault current to flow.
Figure 1
Design Note 1:
the zig-zag transformer when specified.
Design Note 2:
connection to the existing power system, typically at the
main transformer or switchgear. See Figure 1.
Design Note 3:
greater than the system capacitive charging current
(See Section I).
Design Note 4:
systems depend on the integrity of the NGR. PGN-1000 Series
has an option for resistor monitoring, whereas the PGN-3000
Series includes resistor monitoring.
y
The PGN Families of NGR systems include
The PGN system requires a 3-phase
The resistor let-through current must be
Protection, coordination, and annunciation
PGN-1000 or
PGN-3000
Systems
POWR-GARD
Converting to a resistance Grounded System
50
Convert Solidly-Grounded to Resistance
Grounded Systems
Resistance grounding protects a system against Arc Flash
Hazards caused by ground faults and it provides a method
for continuous operation or an orderly shut-down procedure.
(Ground faults are estimated to be 95% of all electrical faults.)
Since the neutral point of the power source is available, the
solid connection between neutral and ground is replaced with a
grounding resistor. This resistor physically limits the ground fault
current to a pre-determined value, typically 5A for 480V systems
(the system capacitive charging current is usually less than 3A).
By limiting the ground fault current to 5A or less, there are no
Arc Flash Hazards associated with ground faults. This allows for
continuous operation during the first ground fault.
During a ground fault on a Resistance Grounded (RG)
system, a voltage shift occurs (the same shift experienced on
Ungrounded systems). The faulted phase collapses to ~0V
and the non-faulted phases rise to line-to-line voltage with
respect to ground and the neutral point rises to line-to-neutral
voltage with respect to ground.
Figure 2
Design Note 1:
connection to the existing power system, typically at the main
transformer or switchgear. See Figure 2.
Design Note 2:
fully rated at line-to-line voltage with respect to ground. This may
require TVSSs, VFDs, meters, etc. to be reconfigured or replaced.
Design Note 3:
distribution. The neutral cannot be distributed due to its potential
during ground faults. Line-to-neutral loads must be served by a
1:1 isolation transformer or converted to line-to-line loads.
Design Note 4:
than the system capacitive charging current (see Section I).
Design Note 5:
systems depend on the integrity of the NGR. PGN-1000 Series
has an option for resistor monitoring, whereas the PGN-3000
Series includes resistor monitoring.
PGN-1000 or
®
PGN-3000
Systems
Protection Relays
The PGN system requires a neutral
The voltage shift requires equipment to be
The voltage shift also restricts neutral
The resistor let-through current must be greater
Protection, coordination, and annunciation
© 2009 Littelfuse
PGN- 000 or
PGN-3000
y
m
•
POWR-GARD
®
Protection Relay Catalog