Walchem P100 Series Panel-Mount Controller (WCNP / WPHNP / WPHBP)

The Walchem P100 is a panel-mount process controller in a 1/4 DIN (92 x 92 mm) NEMA 4X (IP65) enclosure. With a single universal sensor input it measures conductivity, pH, ORP, ion selective electrodes or disinfectant concentration, and it controls chemical feed through four relay outputs, optional pulse outputs and an isolated 4-20 mA output. The P100 is the current name of the controller earlier sold as the W100P; the operation manual covers the WCN, WPH and W100P series together. As the Walchem distributor in Turkey, Mikron Proses (Üsküdar, Istanbul) supplies matching sensors and spare parts and provides application consulting for sensor selection, retrofit and calibration.

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Model codes

The first letters of the model code select the sensor input and the rest select the outputs (WCNP, WPHNP and WPHBP are the model families listed in the brochure):

Model	Sensor input	Outputs
WCNP-110-A	Universal input: contacting or electrodeless conductivity, amplified pH/ORP, disinfection	Four dry contact relays, one 4-20 mA output
WCNP-120-A	Universal input, as above	Two dry contact relays, two opto-isolated pulse outputs, one 4-20 mA output
WPHNP-110-A / 120-A	Non-amplified pH, ORP or ISE electrode, bare wire terminals	As in the 110 and 120 codes above
WPHBP-110-A / 120-A	Non-amplified pH, ORP or ISE electrode with BNC connector	As in the 110 and 120 codes above

Code 110 stands for four dry contact relays and code 120 for two pulse outputs and two dry contact relays; the letter A adds the isolated analog output, and a final N means that the controller is ordered without a sensor.

Measurement and control

Conductivity is measured with a contacting sensor (four cell constants, up to 0-300,000 µS/cm, ±1% of reading) or an electrodeless toroidal sensor (500-2,000,000 µS/cm). pH is measured from -2 to 16 and ORP or ISE from -1500 to 1500 mV; Walchem disinfection sensors are read from -2000 to 1500 mV. The relays can be used for on/off, time-proportional or timer-based control; with solid-state pulse outputs the controller also provides pulse-proportional and PID control of electronic metering pumps, and the 4-20 mA output can drive valves, actuators or metering pumps or retransmit the reading to a recorder or PLC. One digital input handles a flow switch interlock, a contacting water meter or a paddlewheel flowmeter.

Status and replacement

Walchem lists the P100 (W100P) series among its discontinued-with-support products. For new installations, the wall-mount W100W series and the Intuition-6 series are the current alternatives. See also the Walchem brand page.