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3.15
o
f
vercurrent
ault
Overcurrent fault protection function: it does not use a fuse of type extrafast for the protection of the controller .
In case of short circuit of the load, the device is turned off instantly and is activated the corresponding alarm
indication FUSE_OPEN; if configured (Fr.n different from zero), the load is switched on again for a maximum number
of attempts Fr.n beyond which the device remains off waiting for the manual reset button through front BUT or via the
serial command (bit 109).
456
Fr. n
109*
Reset alarms SHORT_CIRCUIT_CUR-
bit
- DOES NOT replace any of the safeties on the system (such as magnetothermic switches, delay fuses, etc.).
- Protects the controller (and therefore also the load) by replacing the high-speed fuse needed to protect the control
SCRs against faults (without creating any additional cost to replace the fuse and reducing machine downtime).
-Has 2 function states:
√ Normal (On-Off control of load power)
√ Fuse-Open: GFW is open (a short occurred during normal operation).
Conditions of use
-
Breaking capacity: 5 KA - 480V
-
Max. system inductance: 1000 uH
DIFFERENCES AMONG DC PROTECTION DEVICES
Characteristics
Opening technique
• Metal melting
• Contact withdrawal with
preloaded spring
Arc quenching
• Arc in air / sand
• Quenching with silica
sand / spring effect
Opening energy
Depending on model:
(I²t of opening)
• Low – medium – high
Opening time
Depending on model:
• Low – medium – high
Reset
• Replacement
• Labour cost + fuse
change
40
P
f
rotection
unction
R/W
Number of restarts in case of FUSE_OPEN
RENT E FUSE_OPEN
Fuses
• Thermal effect
• Magnetic effect
• Mechanical release
• Mechanical separation of 2 contacts
• Arc in air with quenching in chamber
Depending on model:
• Medium – high
Depending on model:
• Medium – high
• Manual reset
OFF= -
R/W
ON = Reset alarms SHORT_CIRCUIT_CURRENT e FUSE_OPEN
Magnetothermics
80993B_MHW_GFW-Xtra_06-2018_ENG
Overcurrent Fault Protection
Function
• Current threshold (programmable)
• Device shutdown
• No arc in air (current shuts down
in silica)
• Always very low
• Always very low (micro-seconds)
• Manual reset
• Automatic reset ("FR.n" times)
• Remote reset (via serial)
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