The NRR 2-50, NRR 2-51 level controller is used in combination with the NRGT 26-2 level transmitter as a limit switch and water level controller, e.g. in steam boilers and hot water installations or in condensate and feedwater tanks. The level controller indicates when a MIN and MAX water level has been reached, and opens or closes a control valve. The level controller can be combined with the NRGT 26-2 level transmitter.
Function
The NRR2-50, NRR 2-51 level controller processes the level-dependent current signal from the NRGT 26-2 level transmitter. In the controller, these input signals are standardized to and 100% of the boiler measuring range and shown as an actual value on the 7-segment LED display. Level controller NRR 2-50: The level controller works with an electrically actuated control valve as a 3-position stepping controller with proportional-plus-integral control action (PI controller). If the actual value deviates from the set point, the electric actuator is triggered by two output contacts, and two flashing LEDs indicate whether the control valve is opening or closing. The controller can be configured for fill or drain control. A further output contact indicates when a MIN or MAX water level is reached (the desired function is switch-selectable). After the off delay has elapsed, the output contact switches and the MIN or MAX LED lights up.
Level controller NRR 2-51: The level controller works with an electro-pneumatically actuated control valve as a continuous controller with proportional-plus-integral control action (PI controller). If the actual value deviates from the set point, it outputs a current of 4-20 mA as manipulated variable Y. The controller can be configured for fill or drain control. If the MIN or MAX water level is reached, after the off delay the MIN or MAX output contact switches in the level controller, and the MIN or MAX LED lights up.
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