Flowserve NRS1-9 - Manual (Page 8)

8
Explanatory Notes
Description
Function
Self-monitoring water level controller & limiter with automatic self-testing routine
designed for use in conjunction with level electrode NRG 16-36. This equipment
combination controls the water level, detects the max. allowable water level
(high level alarm) and the min. allowable water level (low level alarm).
Application in compliance with the German regulations for use in steam and
hot-water plants according to TRD 602 and TRD 604, sheets 1 and 2.
The switching controller NRS 1-9 features a two channel circuit and is provided with
a self-monitoring and routine testing function in accordance with DIN 57116/VDE
0116. The two channels are designed to monitor the operation of each other
(redundancy). The periodic self-checking logic unit checks the integrity of the cable
between the electrode and the switching controller, and the two channel circuits for
malfunction.
Unless it finds a fault, this internal test does not interfere with the output contacts of
the controller and therefore the boiler operation is not interrupted.
A manual test push button is also provided. When the push button “TEST 1” is
pressed, it simulates a fault in the electrode. There is also a toggle switch “TEST 2/
Inspection” for checking the function of the self-checking circuitry. The output
contact relays of the switching controller are of the normally closed type and will
therefore signal alarm condition in the event of mains failure.
The switching controller can signal the following four operating conditions:
■ Normal operation (feedwater control)
■ Alarm (high water level)
■ Alarm (low water level)
■ Alarm (fault in switching controller or level electrode)
A green LED indicates power ON. Low water level alarm or malfunction of the low
water level limiter system is indicated by the two red LEDs. The failure of one
channel (loss of redundancy) is signalled by the lighting up of one red LED. The
other green LED indicates feedwater pump is running. High water level alarm is
signalled by another red LED.
The use of SMART combination electrode NRG 16-36 in conjunction with switching
controller NRS 1-9 provides fail safe protection against a first fault, i. e. the system
will still continue to provide the safety function even after the occurrence of a first
fault.
Scope of supply
NRS 1-9
1 Water level controller/water level limiter (plug-in unit for installation in control
cabinets)
1 Installation manual