Schweitzer Engineering Laboratories SEL-751 - Figure 4.66 Inverse Time-Overvoltage Element Curves; Table 4.41 Specification of Inverse-Time Overvoltage Protection Element

4.105
Date Code 20170927 Instruction Manual SEL-751 Relay
Protection and Logic Functions
Group Settings (SET Command)
The curve option COEF is the user-programmable curve. Set the coefficient
related settings 59InCFA, 59InCFB, and 59InCFC to realize the curve that
meets your application needs. Table 4.41 shows the parameters of the three
curves. Note that when 59InCRV is set to CURVEA, CURVEB, or CURVEC
the coefficient related settings 59InCFA, 59InCFB, and 59InCFC are forced to
the values shown in Table 4.41 and hidden.
When the operating quantity remains lower than the pickup level, 59InP, then
the output remains deasserted. If the operating quantity gets lower than the
pickup level for the reset time setting, 59InTTR, then the time integrator resets
to 0.
Figure 4.66 Inverse Time-Overvoltage Element Curves
Table 4.41 Specification of Inverse-Time Overvoltage Protection Element
Curve Description
Curve Defining Constants
59InCFA 59InCFB 59InCFC
Curve A 3.88 0.96 2
Curve B 5.64 0.24 2
Curve C 0.14 0 0.02
Programmable Curve 0.00–6.00 0.00–3.00 0.01–3.00
n = 1, 2, 3, or 4.
Time Dial = 1
Time Dial = 2
Time Dial = 5
Time Dial = 10
Time Dial = 1
Time Dial = 2
Time Dial = 5
Time Dial = 10
Time Dial = 1
Time Dial = 2
Time Dial = 5
Time Dial = 10
Curve A
Curve B Curve C
Multiples of Pickup Multiples of Pickup Multiples of Pickup
Time in Seconds