Electrical Connections - Hach WPC-21 Manual Del Usuario

To prevent shock hazards from ground currents in inadequate ground systems, connect the shield at
only the instrument end. Do not connect the shield wire at both ends.

Electrical connections

Electrocution hazard. Do not use conduit to supply power. The enclosure does not have a protective
Earth Ground (PE) connection.
Electrocution hazard. Always remove power to the instrument before making electrical connections.
Figure 4 shows the wiring connections and general wiring procedure.
Make all electrical cable connections through the strain-relief fittings. To keep the enclosure rating:
• Do not put more than one cable (or two wires) through a strain-relief fitting.
• Make sure that the strain-relief fittings that are unused have rubber cable plugs in them. Use
strain-relief fittings of the appropriate environmental rating.
Obey all codes and regulations for wiring. Tighten the strain relief fittings to hold the cables securely.
Figure 4 Wiring overview
1 Analog input/output connections
2 Communication connections (RS232 and RS485)
Connect the analog outputs (optional)
Two 4–20 mA analog outputs (AO1 and AO2) are available at the J3 connector. The analog output
signal is proportional to the counts/mL of the channel. The counts/mL for Channel 1 is represented
on AO1. The counts/mL for Channel 2 is represented on AO2.
Connect a current receiving device to each analog output with 24–28 AWG wire. Refer to
If the current receiving device(s) has a load resistor of 500 ohms or more, supply external voltage
(40 VDC maximum) to Vext– and Vext+ of the J1 connector to supply sufficient voltage to the current
receiving device.
10 English
D A N G E R
D A N G E R
3 Alarm connections (digital outputs)
4 Strain-relief fitting for external connections (4x)
Table 1.