ABB RELION 670 Series Technical Manual page 1392

Generator protection

Hide thumbs Also See for RELION 670 Series:

Table of Contents

Inverse time characteristics

twenty times the set current pickup value. Note that the operating time value is dependent on the

selected setting value for time multiplier k.

In addition to the ANSI and IEC standardized characteristics, there are also two additional inverse

curves available; the RI curve and the RD curve.

The RI inverse time curve emulates the characteristic of the electromechanical ASEA relay RI. The

curve is described by equation 233:

EQUATION1647 V1 EN-US

Pickupn is the set pickup current for step n

The RD inverse curve gives a logarithmic delay, as used in the Combiflex protection RXIDG. The

curve enables a high degree of selectivity required for sensitive residual ground-fault current

protection, with ability to detect high-resistive ground faults. The curve is described by

equation 234:

EQUATION1648 V1 EN-US

Pickupn is the set pickup current for step n,

If the curve type programmable is chosen, the user can make a tailor made inverse time curve

according to the general equation 235.

EQUATION1640 V1 EN-US

is set time multiplier for step n

is the measured current

is set time multiplier for step n and

is the measured current

1MRK 502 066-UUS B

(Equation 233)

(Equation 234)

(Equation 235)

Technical manual

Chapters

Table of Contents