ABB RET670 Applications Manual

3.8.5.1 Application
The Voltage differential protection VDCPTOV (60) functions can be used in some
different applications.
• Voltage unbalance protection for capacitor banks. The voltage on the bus is
supervised with the voltage in the capacitor bank, phase- by phase. Difference
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
219 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 219: 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.
1MRK504116-UUS C Section 3
IED application
537
Application manual

ABB RET670 Specifications

General

Rated Frequency	50/60 Hz
Inputs	Analog and binary inputs
Application	Protection of power systems
Communication Protocols	IEC 61850, DNP3, Modbus
Operating Temperature Range	-25°C to +55°C
Mounting	Rack mounted
Number of Binary Inputs	Up to 48
Number of Binary Outputs	32
Protection Functions	Overcurrent Protection
Outputs	Binary outputs
Enclosure	IP 54
Type	Line Differential Protection
Number of Analog Inputs	24