RI and RD-type inverse-time characteristics - Arc protection - Back-up protection - Feeder protection - Motor protection - Technical Manual - REX610 Protection and control - 1.2 - ANSI - IEC - 17.02.2023

REX610 Technical Manual

The RI-type simulates the behavior of electromechanical relays. The RD-type is an earth-fault specific characteristic.

The RI-type is calculated using the formula

Figure 1. Equation
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The RD-type is calculated using the formula

Figure 2. Equation
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t[s] Operate time (in seconds)
k Set Time multiplier
I Measured current
I> Set Start value
Figure 3. RI-type inverse-time characteristics
Figure 4. RD-type inverse-time characteristics