Overload Relays General data 1) Exception: up to size S3, only stand-alone installation is possible. 2) Alternatively available for screw terminals.
5 Siemens · 2009 Features Benefits 3RU11 3RB20/3RB21 3RB22/3RB23 3RU11 3RB20/3RB21 3RB22/3RB23 Design of load feeders Short-circuit strength up to 100 kA at 690 V (in conjunction with the corresponding fuses or the corresponding motor starter protector) • Provides optimum protection of the loads and ope- rating personnel in the event of short-circuits due to insulation faults or faulty switching operations ✔ ✔ ✔ Electrical and mechanical matching to 3RT1 contactors • Simplifies configuration • Reduces wiring outlay and costs • Enables stand-alone installation as well as space- saving direct mounting ✔ ✔ ✔1) Straight-through transformers for main circuit2) (in this case the cables are routed through the feed-through openings of the overload relay and connected directly to the box terminals of the contactor) • Reduces the contact resistance (only one point of contact) • Saves wiring costs (easy, no need for tools, and fast) • Saves material costs • Reduces installation costs -- ✔ (S2 ...
S6) ✔ (S00 ...
S6) Spring-type terminal connection sys- tem for main circuit2) • Enables fast connections • Permits vibration-resistant connections • Enables maintenance-free connections ✔ (S00) -- -- Spring-type terminal connection sys- tem for auxiliary circuits2) • Enables fast connections • Permits vibration-resistant connections • Enables maintenance-free connections ✔ ✔ ✔ Other features Temperature compensation • Allows the use of the relays at high temperatures without derating • Prevents premature tripping • Allows compact installation of the control cabinet without distance between the devices/load feeders • Simplifies configuration • Enables space to be saved in the control cabinet ✔ ✔ ✔ Very high long-term stability • Provides safe protection for the loads even after years of use in severe operating conditions (✔) ✔ ✔ Wide setting ranges • Reduce the number of variants • Minimize the engineering outlay and costs • Minimize storage overhead, storage costs, tied-up capital -- ✔ (1:4) ✔ (1:10) Trip class CLASS 5 • Enables solutions for very fast starting motors re- quiring special protection (e.
g. Ex motors) -- ✔ (only 3RB21) ✔ Trip classes > CLASS 10 • Enables heavy starting solutions -- ✔ ✔ Low power loss • Reduces power consumption and energy costs (up 98 % less power is used than for thermal over- load relays). • Minimizes temperature rises of the contactor and control cabinet – in some cases this may eliminate the need for controlgear cabinet cooling. • Direct mounting to contactor saves space, even for high motor currents (i. e. no heat decoupling is required). -- ✔ ✔