Watts HF scientific CLX- XT, Owner'S Manual

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CLX-XT (28652) Page 11
REV 5 (5/2020)
4.3.2 Cooling Chamber Power
Power must be connected to the cooling control box mounted on the top right side
of the cabinet. The requirements are 100-240VA, 47-63 Hz and 100VA. A circuit
breaker must be placed prior to the power connection in close proximity and within
easy reach to allow for service. This circuit breaker must be marked to indicate that
it is a disconnecting means for the cooling circuit for
the instrument. All wiring to the cooling chamber
must be rated for 90 ˚ C or higher.
This supply is separated from the instrument power
connection because the cooling chamber must be
operated full time to prevent premature degradation
of the indicator reagent. Power cable enters from the
bottom of the cabinet. The connection block is
marked N for Neutral and L for line the third symbol
indicates a secure earth ground. The removable
terminal block is suitable for wire gauges 18 to 12
AWG. In addition a chassis common earth bond point is provided on the chassis
below the instrument safety access cover. 4.3.3
4.3.3 RS-485
The RS-485 half-duplex (2-wire) digital
interface operates with differential levels that
are not susceptible to electrical interferences.
This is why cable lengths up to 3000 ft can be
implemented. The last device on each bus may
require terminating with a 120 ohm resistor to
eliminate signal reflection on the line. Do not
run RS-485 cables in the same conduit as
power. Set-up of the RS-485 is covered in 7.3
Configuring the RS–485 Port
To prevent damage to the instrument, ensure that power is disconnected prior to
making connections. For ease of connecting, remove the plug-in terminal block.
Connections are labeled beside this termination on the PC board. The
recommended cable is 22 AWG shielded twisted pair. The grey terminal block is
removable to assist in making connections.
4.3.4 Relays
The Alarm 1 and Alarm 2 relays are mechanical relays rated at 240 VAC 2A.
Please note that the relays are labeled NO (Normally Open), NC (Normally
Closed) and C (Common). As these alarms are configured fail-safe, the normal
condition is with power applied to the CLX-XT and in a non-alarm condition.
Operation of these alarms is covered in section 7.4 Configuring the Alarms .
The lever operated terminal blocks are rated for wire gauges 28-14.