Xylem CL500 ONLINE CHLORINE ANALYZERS - Manual (Page 14)

CL500 (2/08) Page 10
REV 2.0
4.3.3 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 CL500 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.
4.3.4 4-20 mA
The 4-20 mA output is driven by a 15 VDC power source and can drive recorder
loads up to 600 ohms. Transformer isolation is provided on the CL500. Do not run
4-20 mA cables in the same conduit as power. Operation of this output is covered
in section 7.1 Setting the 4-20 mA.
To prevent damage to the instrument, and for general safety ensure that power is
disconnected to the CL500 prior to making any connections. Polarities of the
connections are labeled beside this termination on the PC board.
The recommended cable is 22 AWG shielded twisted pair. To prevent ground
loops, connect the shield at either the CL500 or at its destination, but not both.
The grey terminal block is removable to assist in making connections.
4.3.5 RS-485/4-20 mA cable Ferrite
To meet IEC requirements for RF radiated immunity a clamp-on type ferrite is
supplied in the accessory kit. It should be placed on the RS-485 or 4-20 mA cable
outside, as close as possible to the CL500. If both outputs will be used, an
additional ferrite will be needed and can be ordered from Global Water
Instrumentation Catalog number 24560GW.
4.4 Installing Reagents
The CL500 will require that two reagents be installed prior to operation. These are a
buffer and an indicator. Be sure the correct, prepared reagents are on hand as different
reagents are required to read Free than Total chlorine residual. For reagent preparation
refer to section 10.2 Replacing and Installing the Reagents.