Thermal Overload Element - Toshiba GRL100-701B Instruction Manual

Long Time Inverse
120
t = T ×
(I/Is)−1
Standard Inverse
0.14
t = T ×
0.02
(I/Is)
Very Inverse
13.5
t = T ×
(I/Is) − 1
Extremely Inverse
80
t = T ×
2
(I/Is)
where,
t = operating time
I = fault current
Is = current setting
T = time multiplier setting

2.16.7 Thermal Overload Element

Thermal overload element operates according to the characteristics defined in IEC60255-8. (Refer
to Figure 2.6.1 and Appendix P.)
2.16.8 Out-of-Step Element OST
The OST element detects the out-of-step by checking that the voltage phasor V B of the remote
terminal transits from the second quadrant (α-zone) to the third quadrant (β-zone) or vice versa
when the voltage phasor V A of the local terminal is taken as a reference.
V B is further required to stay at each quadrant for a set time (1.5 cycles) to avoid the influence of
any VT transient.
Positive phase voltages are used and valid for V A and V B when their amplitudes are larger than
1V.
− 1
− 1
V B
α -zone
β -zone
Figure 2.16.8.1 Out-of-Step Element
 145 
1V
V A
6 F 2 S 0 8 5 0