US2, US4, US6 Electronic step controllers

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4 98 US, US4, Electronic step controllers The electronic step controllers are used in linear mode to switch devices (pumps, compressors, humidifiers and fans etc.) on and off in stages.

1 4 98 US, US4, Electronic step controllers The electronic step controllers are used in linear mode to switch devices (pumps, compressors, humidifiers and fans etc.) on and off in stages. Switch-on time delay feature (typically used to prevent current surges after a power failure) can be disabled Preset switch-on points Fixed switching differential The US4 and can be switched to C-step mode. This gives binary control, switching the low stages more frequently than the high stages. Suitable for use with controllers in the CLASSIC, DESIGO 30 and INTEGRAL RSA and RSC ranges. Types US US4 -step controller, Linear mode 4-step controller, Linear or C-step mode, selected by switch 6-step controller, Linear or C-step mode, selected by switch Technical data Supply voltage With safety low voltage (SELV) Nominal voltage AC 4 V, 50 / 60 Hz Tolerance + 5 / 0 % Power consumption US : 4 VA / US4 : 6 VA / : 8 VA Primary fuse None Signal input DC V control signal Signal outputs: US, US4 Volt-free change-over contacts Single throw volt-free contact Contact rating per stage Max. AC 50 V Max. 5 A resistive Max. A inductive, cosϕ 0.4 Min. admissible load: 0 ma at DC 5 V Max. voltage against earth AC 50 V Switching voltages: US DC / 3.3 V (linear mode) US4 DC / 3.3 / 4.6 / 5.9 V DC / 3.3 / 4.6 / 5.9 / 7. / 8.5 V Switching differential (linear mode) DC 0.5 V all stages Switch-on delay (linear mode) 5 s per stage, can be disabled Principle of operation: Linear Relays energised with rising voltage. C-step Relays driven in binary sequence. Connections: Connection terminals Plug-in screw terminals, x.5 mm Max. cable length See installation guidelines Weight (including packaging): US 0.35 kg US4, 0.40 kg Dimensions (W x H x D) 08 x 3 x 5 mm General ambient conditions: Usage Built-in unit for control panel mounting Temperature range Operation C Transport and storage C Ambient humidity %rh, non-condensing Mounting Snapped onto DIN rail (EN x 7.5) or screwed to a flat surface Safety Product safety EN600 Overvoltage category II Contamination level Electrical safety SELV-E (PELV to IEC ) Function Type B to EN600 Conformity This product meets the requirements for marking Siemens Building Technologies CAN498E /.998 Landis & Staefa Division /6

2 Principle of operation ON 5007 Switch : ON = Switch-on delay enabled Switch : Selects Linear or C-step ON = C-step Switch on the US has no function. "Linear" mode The US.. electronic step controllers operate over a DC 0 0 V control signal range. The switch-on points and switching differential are preset and cannot be adjusted. If required, a preset switch-on delay can be enabled. When used in conjunction with controllers whose parameters are set in software (e.g. certain DESIGO 30 controllers and the INTEGRAL RSA and RSC controllers) the switching voltages, switching differential and switchon delay are set in the controllers themselves, in which case the switch (Switch on the US.. step controller) must be set to OFF. Initially, on a rising voltage signal, step is switched on when the preset voltage value is reached and the time delay has elapsed. The time delay for step is also initiated, and the switch-on process is repeated for step and the subsequent steps in the same way. With a falling control signal, the steps switch off in reverse sequence without a time delay, and in accordance with the voltages defined by the switching differential. The switch states are indicated by LEDs on the controller. C-step mode In C-step mode, the loads of electric heating coils are divided in binary fashion, and controlled so that large loads are switched as infrequently as possible, with smaller loads being switched more often. This produces eight steps for the US4, and 3 steps for the. See the calculation examples on page 5. Construction The step controller comprises a metal housing and a PCB on which the relays are located. Two-part plug-in terminal blocks are provided for the external connections. The switches used to enable and disable the switch-on delay and to select the mode of operation (linear / C-step) are locate on the top right of the PCB. Mounting / Installation Ensure free access to the connection terminals. To dissipate the heat generated during operation, adequate air circulation must be allowed for max. ø 4,5 mm Rail mounting The controller base is designed for snap-mounting on a DIN rail. Rail type: EN x 7.5 Surface mounting Four clear screw-holes are provided for surface mounting. CAN498E /.998 Siemens Building Technologies /6 Landis & Staefa Division

3 Dimensions [mm] , Terminal layout US US TE NS LS AC 4 V supply TE NS LS AC 4 V supply TE NS LS AC 4 V supply Y DC V input Y DC V input Y DC V input 6 6 Relay Relay 6 6 Relay Relay Relay Relay Relay 3 9 Caution 7 7 Relay 3 7 Relay 4 Note the technical date for the relay contacts: AC 50 V / 5() A NS = System ground 77 Relay Relay 5 Relay 6 Connection diagrams US.. with CLASSIC and DESIGO 30 AC 4 V supply NS LS 40 RK.. / RCK US.. 0 Siemens Building Technologies CAN498E /.998 Landis & Staefa Division 3/6

4 US.. with INTEGRAL RSA and RSC AC 4 V supply NRUE/A, NRUF/A NRUT/A NRK6 (-B/-TEL) L (~) N ( ) GND US.. 0 Switching diagrams (Operation in "linear" mode) US U E V 3,3 V US U E V 3,3 V 4,6 V 5,9 V U E V 3,3 V 4,6 V 5,9 V 7, V 8,5 V CAN498E /.998 Siemens Building Technologies 4/6 Landis & Staefa Division

5 Selection guide for C-step control Controllers PI- (PDPI-) controllers should be used, e.g. CLASSIC RK..-L or RK88T DESIGO 30 RCK.. Controller settings: x c : Increase in temperature across heating coil (design value) Voltage range : DC... 0 V (universal) Step controller The number of steps is determined not by the total load, but by the temperature differential across the heating coil and the required level of control accuracy. Comfort is also a factor, and supply air temperature fluctuations with a of more than 4 K should be avoided. The greater the number of steps, the smaller the fluctuation. [K] 4 Max. temperature change per step 5058EN Type No. of No. of Binary division stages relays US4 8 4 I II I II US4 Example 3 steps with 6 relays 8 steps with 4 relays Example Temp. differential across heating coil Heating coils The loads switched at steps and must be equal. Each subsequent step must be less than or equal to the sum of the previous steps. The load for each step should be distributed equally over the three phases. Example Given: Heating coil output = 4 kw Temperature differential across heating coil = 5 K Max. desired accuracy =.5 K (per step) Selected step controller: US4 (see diagram) Calculation of smallest load: P / n = 4 kw / 8 steps = 3 kw Load distribution: Load = 3 kw Load = 3 kw Load 3 = 6 kw Load 4 = kw Total: 4 kw Example Given : Heating coil output 75 kw Temperature differential across heating coil = 5 K Desired accuracy =.5 K (per step) Selected step controller: (see diagram) Calculation of smallest load: P / n = 75 kw / 3 steps =.34 kw Load distribution: Load = 3 kw Load = 3 kw Load 3 = 6 kw Load 4 = kw Load 5 = 8 kw Load 6 = 33 kw Total: 75 kw Siemens Building Technologies CAN498E /.998 Landis & Staefa Division 5/6

6 998 Siemens Building Technologies Ltd. CAN498E /.998 Siemens Building Technologies 6/6 Landis & Staefa Division

Electronic Step Controller

4 915 Electronic Step Controller, Adjustable switch-on delay (typically used to prevent current surges on startup and after a power failure) Adjustable switch-on points Adjustable switching differential