Resetting Overvoltage - Hitachi Relion 670 Series Operation Manual

Section 8
REX060 injection unit LHMI
Table 18:
8.1.5.5

Resetting overvoltage

Stator and rotor injection outputs are protected against voltages exceeding maximum operating range by
a relay blocking the injection circuit. This blocking is controlled by measuring the stator and/or rotor
voltage, and remains blocked until manually reset. The blocking remains in the non-volatile memory
when the IED is powered off.
Overvoltage blocking is indicated by a symbol shown in
Resetting procedure:
1. Power off the REX060.
2. Press and hold the C and Key-lock buttons.
3. Power on the REX060 and wait until the status indication Over-voltage (symbol) disappears from
the display.
4. Release the C and Key-lock buttons.
REX060 stator and rotor overvoltage protection of injection circuit
Both rotor and stator have two levels of protection, injection circuit interruption controlled by the voltage
sense input and a fuse for over-current protection. The voltage controlled interruption, overvoltage, will
normally occur prior to interruption by fuse and the reset sequence is described above. A blown fuse
requires module disassembling to replace the fuse (F 4 A 250 V for stator and F 160 mA 250 V for rotor).
However, if this occurs it is recommended to identify the reason for the over-current and take necessary
actions to reduce the current before restarting the unit. The problem must be outside the injection unit
since this unit cannot provide enough energy to blow the fuse.
REX062 input protection
REX062 limits overvoltage by a varistor at the injection output to stator. Normally , REX060 will interrupt
the injection circuit in case of excessive over-current in the injection chain. Fuse within REX062 is an
additional protection in case of failure within REX062 during over-voltage condition.
A blown REX062 fuse requires a module disassembling to replace the fuse (F 6.3 A 250 V). However, if
this occurs it is recommended to identify the reason for the over-current and do needed actions to reduce
the current.
80
Stator gain
VmaxEF [V]
240
200
160
≤ 120
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Note
Default value
Table 16.
1MRK500127-UUS Rev. M
GUID-656B534F-3F83-4B35-8020-F9875FF82DED v3
670 series
Operation manual