Hach SC4500 Basic User Manual page 19

For AC controllers, use the relays at high voltage. For DC controllers, use the relays at low voltage.
Refer to Specifications
high and low voltage.
Relay terminal connections to the mains circuit in permanent connection applications must have
insulation rated for a minimum of 300 V, 90 °C (194 °F). Terminals connected to the mains circuit
with a power cord connection must be double insulated and rated 300 V, 90 °C (194 °F) at both the
inner and outer insulation levels.
Figure 10 Connect the relays
Terminal Description
1 Relay 2, NC
2 Relay 2, common
3 Relay 2, NO
NC = normally closed; NO = normally open
4.3.5 Install an expansion module
Explosion hazard. This manual is only for installation of the unit in a non-hazardous location. For
installation of the unit in hazardous locations, use only the instructions and approved control drawing
provided in the hazardous location installation manual.
Expansion modules for analog outputs, analog inputs, analog sensors and Profibus communication
are available for the controller. Refer to the documentation supplied with the expansion module for
additional information.
on page 3 for the relay specifications. Do not configure a combination of both
Table 4 Wiring information—relays
W A R N I N G
Terminal Description
4 Relay 1, NC
5 Relay 1, common
6 Relay 1, NO
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