Siemens SG8158-00 manual Figure A.11 Moderately Inverse Overvoltage Curve

Appendix A: Trip Curves & Equations

Over/Undervoltage Coefficients

Curve Type

Des.

A1

B1

N1

tr

Inverse

0.51

-1.75

0.50

---

Mod. Inverse

0.51

-0.45

0.50

---

￿￿Very Inverse

0.51

1.75

0.50

---

The A, B, and N coefficients are for the standard relay formula

Table A.2 Under/Overvoltage Coefficients

v

1.5:

AD

For1.01 ≤ -----≤

T = ------------------------ + BD

vp

⎛

v

⎞

N

⎝

-----

⎠

– 1

vp

⎛

v

:

AD

⎞

For⎜

----- > 1.5

T = ------------------------- + BD⎟

⎝ vp

( 1.5 )

N

–

1

⎠

T = time to trip, in seconds

v = measured input voltage

vF= pickup value (tap setting)

⎛

v

⎞

⎜

------

⎟ = multiple of pickup setting

⎝ v

p

⎠

D = time dial setting, 0.1 to 9.9 in steps of 0.1

A, B, N = constants for inverse curves

Equation A.5 Overvoltage Equation

1000

(Seconds)	100							TimeDial
	10
							5.0
							9.9
toTrip
Time							2.0
	1							1.0
								0.5
								0.2
							0.1
	0.1
	1	1.1	1.2	1.3	1.4	1.5	1.6

Multiples of Pickup

Figure A.11 Moderately Inverse Overvoltage Curve

1000

A

For 0.5 ≤ -----v≤ 1.5:			T =	------------------------		AD			+ BD
		vp		⎛ v		⎞		N
				⎝ v----p-		⎠		–	1
	⎛								⎞
For⎜ -----v≤ 0.5:			T = -------------------------	AD					+ BD⎟
	⎝ vp		( 1.5 )		N		–	1	⎠
T = time to trip, in seconds
v = measured input voltage
vF= pickup value (tap setting)
⎛		⎞
⎜ --v----		⎟ = multiple of pickup setting
⎝ v	p	⎠

D = time dial setting, 0.1 to 9.9 in steps of 0.1 A, B, N = constants for inverse curves

Time Dial

9.9

5.0

2.0

1.0

0.5

0.2

0.1

100

(Seconds)

10 Tripto

Time

1

0.1

0.4 0.5 0.6 0.7 0.8 0.9 1.0

Multiples of Pickup

Equation A.6 Undervoltage Equation Figure A.12 Moderately Inverse Undervoltage Curve

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