indicates a fault, either short-circuited or open element in the capacitor bank. It is
mainly used on elements with external fuses but can also be used on elements with
internal fuses instead of a current unbalance protection measuring the current
between the neutrals of two half’s of the capacitor bank. The function requires voltage
transformers in all phases of the capacitor bank. Figure
293 shows some different
alternative connections of this function.
Vd>L1
Ph BPh C
V1
V2
Vd>A
Ph BPh C
V1 V2
Ph C
Ph B
en06000390_ansi.vsd
Single grounded wye
Double wye
ANSI06000390 V1 EN
Figure 293: Connection of voltage differential protection VDCPTOV (60) function to
detect unbalance in capacitor banks (one phase only is shown)
VDCPTOV (60) function has a block input (BLOCK) where a fuse failure supervision (or
MCB tripped) can be connected to prevent problems if one fuse in the capacitor bank
voltage transformer set has opened and not the other (capacitor voltage is connected to
input V2). It will also ensure that a fuse failure alarm is given instead of a Undervoltage
or Differential voltage alarm and/or tripping.
Fuse failure supervision (SDDRFUF) function for voltage transformers. In many
application the voltages of two fuse groups of the same voltage transformer or fuse groups
of two separate voltage transformers measuring the same voltage can be supervised with
this function. It will be an alternative for example, generator units where often two voltage
transformers are supplied for measurement and excitation equipment.
1MRK 506 369-UUS - Section 10
Voltage protection
Line distance protection REL670 2.2 ANSI 587
Application manual
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