Solid-State Switching Devices for Resistive Loads 3RF29 Function Modules Power regulators ■ Overview SIDAC reactors for generalized phase control mode Power regulators for 3RF2 single-phase solid-state swit- ching devices The power regulator is a function module for the autonomous power control of complex heating systems, for the operation of loads with temperature-dependent resistors and for simple indi- rect control of temperature. The power regulator can be used on the instantaneously swit- ching 3RF21 and 3RF23 solid-state switching devices (single- phase).
If only the full-wave operating mode is used, the power regulator can also be used on the zero-point-switching solid- state relays and contactors. Setpoint selection The following functions have been integrated: • Power controller with proportional-action control for adjusting the power of the connected load. Here, the setpoint value is set with a rotary knob on the module as a percentage with re- ference to the 100 % power stored as a setpoint value. Changes in the mains voltage or in the load resistance are compensated in this case. • Inrush current limitation: With the aid of an adjustable voltage ramp, the inrush current is limited by means of phase control.
This is useful above all with loads such as lamps which have an inrush transient current. • Load circuit monitoring for detecting load failure, alloyed power semiconductors, lack of voltage or a break in the load circuit. The setpoint selection is set either internally with the right-hand potentiometer P to 0 ... 100 % on the module or externally using the analog input 0 ... 10 V. External setpoint selection At 0 % on the potentiometer the setpoint selection is set using an external 0 ... 10 V analog signal (terminals IN / 0 ... 10 V). The device is switched on and off via the power supply (terminals A1/A2). Internal setpoint selection Above 0 % the setpoint is set using the potentiometer.
To allow this, the potential at terminal A1 must additionally be applied at the IN terminal. After removal of the "ON" signal, the switching module is switched off. Inrush current limitation The ramp time (t R ) for a voltage ramp on switching on is set with the left potentiometer for the purpose of inrush current limitation. If a time longer than 0 s is set, the device operates according to the generalized phase control principle. If 0 s is set, there is no voltage ramp and the device operates according to the principle of full-wave control.
■ Design Mounting Easy snapping onto the 3RF21 solid-state relays or 3RF23 solid- state contactors establishes the connections to the solid-state switching devices. Because of the special design, the straight- through transformer of the function module covers the lower main circuit connection. The cable to the load is simply pushed through and secured with the terminal screw. Load fault If upon switching on with voltage applied the current flowing is not greater than the leakage current of the control, the device triggers a load fault. The fault relay is activated and the "Load" LED lights up.
■ Function Power control Thyristor fault The power regulator adjusts the current in the connected load by means of a solid-state switching device depending on a setpoint value. Changes in the mains voltage or in the load resistance are thus compensated by the power regulator. The setpoint value can be predefined externally as a 0 to 10 V signal or internally by means of a potentiometer. Depending on the setting of the po- tentiometer ( t R ), the adjustment is carried out according to the principle of full-wave control or generalized phase control. If a current greater than the leakage current of the control is measured in the deenergized state, the device triggers a thyris- tor fault.
The fault relay is activated and the "Thyristor" LED lights up. Power system fault If no current is measured in the energized state, the device trig- gers a power system fault. The fault relay is activated and the "Supply" LED lights up. Full-wave control Startup In this operating mode the output is adjusted to the required set- point value changing the on-to-off period. The period duration is predefined at one second. Pressing the "Teach" button switches the device on; the current through the solid-state switching device and the mains voltage are detected and stored. The resultant output is taken as the 100 % output for the setpoint selection.
During this process the two lower red LEDs flash alternately. Simultaneous continuous light from the three red LEDs indicates the completion of the "Te- ach" process. Generalized phase control In this operating mode the output is adjusted to the required set- point value by changing the current flow angle. The half-waves of the current are adjusted to produce the selected setpoint va- lue of the power at the load. In order to observe the limit values of the conducted interference voltage for industrial networks, the load circuit must include a re- actor with a rating of at least 200 µH.
The "Teach" button can also be used to switch on the connected solid-state switching device briefly for test purposes. In this case the "ON" LED is switched on. 50 Siemens · 2009 Power control regulators, power regulators Reactors Rated voltage Type Up to 230 V Up to 480 V Up to 660 V 3RF2904-0KA. 4EM4700-8CB00 4EM4915-0CB00 4EM5007-7CB00 3RF2920-0KA./-0HA. 4EM4700-8CB00 4EM4915-0CB00 4EM5007-7CB00 3RF2950-0KA./-0HA. 4EM5001-1CB00 4EM6100-6CB00 4EM6204-0CB00 3RF2990-0KA./-0HA. 4EM6100-5CB00 4EM5316-7CB00 4EM5412-0CB00