Hitachi Relion REL670 Product Manual page 34

Line distance protection REL670
Version 2.2
Table 10. Basic IED functions, continued
IEC 61850 or function Description
name
ALTMS Time master supervision
ALTIM Time management
CAMCONFIG Central account management configuration
CAMSTATUS Central account management status
TOOLINF Tools information
COMSTATUS Protocol diagnostic
Table 11. Local HMI functions
IEC 61850 or function Description
name
LHMICTRL Local HMI signals
LANGUAGE Local human machine language
SCREEN Local HMI Local human machine screen behavior
FNKEYTY1–FNKEYTY5 Parameter setting function for HMI in PCM600
FNKEYMD1–
FNKEYMD5
LEDGEN General LED indication part for LHMI
OPENCLOSE_LED LHMI LEDs for open and close keys
GRP1_LED1– Basic part for CP HW LED indication module
GRP1_LED15
GRP2_LED1–
GRP2_LED15
GRP3_LED1–
GRP3_LED15
4. Differential protection
High impedance differential protection, single phase
HZPDIF
High impedance differential protection, single phase
(HZPDIF) functions can be used when the involved CT
cores have the same turns ratio and similar magnetizing
characteristics. It utilizes an external CT secondary current
summation by wiring. Actually all CT secondary circuits
which are involved in the differential scheme are connected
in parallel. External series resistor, and a voltage dependent
resistor which are both mounted externally to the IED, are
also required.
The external resistor unit shall be ordered under IED
accessories in the Product Guide.
HZPDIF can be used to protect tee-feeders or busbars,
reactors, motors, auto-transformers, capacitor banks and so
on. One such function block is used for a high-impedance
restricted earth fault protection. Three such function blocks
are used to form three-phase, phase-segregated differential
protection.
34
Additional security logic for differential protection
LDRGFC
M13071-3 v13
Additional security logic for differential protection (LDRGFC)
can help the security of the protection especially when the
communication system is in abnormal status or for example
when there is unspecified asymmetry in the communication
link. It helps to reduce the probability for mal-operation of
the protection. LDRGFC is more sensitive than the main
protection logic to always release operation for all faults
detected by the differential function. LDRGFC consists of
four sub functions:
• Phase-to-phase current variation
• Zero sequence current criterion
• Low voltage criterion
• Low current criterion
Phase-to-phase current variation takes the current samples
as input and it calculates the variation using the sampling
value based algorithm. Phase-to-phase current variation
function is a major one to fulfill the objectives of the startup
element.
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