ABB RET670 Commissioning Manual

_Vdi Ci Icc i Xi= × ×
EQUATION2089-ANSI V1 EN (Equation 112)
The voltage regulation algorithm then increases (for transformer T2) or decreases
(for transformer T1) the measured voltage by Vdi and compares Vi against the
voltage deadband limits V1 and V2 for the purposes of voltage regulation.
Vi VB Vdi= +
EQUATION2091-ANSI V1 EN (Equation 113)
9. To cause a tap change, the calculated value for circulating current voltage
adjustment must offset the injected quantity for bus voltage V
B
so that Vi is outside
the voltage deadband created by setting VDeadband. Expressed by equation 114 and
equation
115.
2Vdi V VB> -
EQUATION2093-ANSI V1 EN (Equation 114)
VB Vset=
EQUATION2095-ANSI V1 EN (Equation 115)
(for the purposes of this test procedure)
Therfore:
_ 2Ci Icc i Xi V Vset× × > -
EQUATION2097-ANSI V1 EN
(Equation 116)
( )
( )
2
_
V Vset
Icc i
Ci Xi
-
>
×
EQUATION2099-ANSI V1 EN (Equation 117)
10. Using the settings for VSet, VDeadband, C (Compensating factor) and Xr2
(transformer short circuit impedance) calculate the magnitude of Icc_i necessary to
cause a tap change command.
11. Inject current equal to I2Base for Transformer 1 and (I2Base - |Icc_i|) for
Transformer 2 so that the magnitude of calculated circulating current will cause a
raise command to be issued for Transformer 2 and a lower command for
Transformer 1. Magnitude and direction of circulating currents measured for each
Section 11 1MRK 504 165-UUS -
Testing functionality by secondary injection
256 Transformer protection RET670 2.2 ANSI
Commissioning 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