Hach SC4500 Basic User Manual page 18

4.3.4 Connect the high-voltage relays
Electrocution hazard. Always remove power to the instrument before making electrical connections.
Potential Electrocution Hazard. Power and relay terminals are designed for only single wire
termination. Do not use more than one wire in each terminal.
Potential fire hazard. Do not daisy-chain the common relay connections or jumper wire from the mains
power connection inside the instrument.
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.
Fire hazard. Relay loads must be resistive. Always limit current to the relays with an external fuse or
breaker. Obey the relay ratings in the Specifications section.
Make sure that the cable sheath goes through the inner side of the enclosure to keep the environmental
rating of the enclosure.
The instrument has two non-powered relays, each with a single-pole change-over contact. For AC
controllers, the wiring compartment is not made for voltage connections more than 264 VAC.
The relay terminals are located behind a high-voltage barrier in the controller enclosure. Do not
remove the barrier while power is supplied to the relay terminals. Do not supply power to the relay
terminals when the barrier is not installed.
Connect each relay to a control device or an alarm device as necessary. Refer to
Table 4 to connect the relays. Refer to the expanded user manual on the manufacturer's website for
additional information.
Refer to Specifications
and the low-voltage input/output circuitry.
The largest gauge wire the power and relay plugs are rated for 1.5 mm
terminals accept 0.75 to 1.5 mm
with an insulation rating of 300 VAC or higher. Insert each wire into the appropriate terminal until the
insulation is seated against the connector with no bare wire exposed. Tug gently after insertion to
make sure that there is a secure connection. If necessary, remove the connector from the PCBA for
easier wiring of the terminals. Flexible wires must have a crimped ferrule or a pin type terminal on the
end.
Note: Make sure that all of the cables stay below the cable limit line printed on the PCBA to prevent interferences
with the high-voltage barrier.
The current to the relay contacts must be 5 A (resistive only load), 1250 VA 125 W (resistive only
load) or less. Make sure to have a second switch available to remove power from the relays locally in
case of an emergency or for maintenance.
18 English
W A R N I N G
W A R N I N G
W A R N I N G
C A U T I O N
N O T I C E
on page 3 for the relay specifications. The relays are isolated from each other
2
(18 to 16 AWG) wire (as determined by load application). Use wire
D A N G E R
Figure 10 and
2
(16 AWG). The relay