TDI-Dynaload Division
WCL488 Series Water Cooled Electronic Loads
Operation & Programming Manual
402828, Rev. B1
Page 117
Symptom
Possible Cause
Explanation/Corrective Action
One or more power modules in
the power tray are overheating.
Send the unit in for service.
During normal
operation the loads red
“ SYS” and “ TEMP”
light.
No cooling fans in WCL.
Check the water flow and the
chiller water temperature as per
manual. Check that the Water
Flow Regulator Valve is wired
correctly and opening. Check any
water flow shutoff relays in your
system.
Load is set in the
constant current mode,
constant power mode
or the constant
resistance mode, and
the expected current
differs from the actual
current.
An audible sound may
also be heard.
System (includes the load,
power source, metering, etc.)
may be oscillating.
Prolonged use of the load while
the system is oscillating may
cause damage to the load.
To check for oscillation, connect
an oscilloscope to the “ CS”
(current sample) with respect to
the S– on the rear terminal strip.
Oscillation is usually caused by
the inductance of the cabling
between the DC source and the
load. This cabling should be as
short as possible and the positive
and negative wires should be
twisted, to reduce the cable
inductance. Also connecting a
capacitor across the loads inputs
can squelch the oscillation.
IEEE address of the load is not
matched with the computer
program being used to
communicate.
Change the IEEE address using
menu item 9 to match the
computer program being used.
Load does not
communicate over the
IEEE bus.
IEEE interconnect cable maybe
loose or defective
Tighten or replace the cable.
Load communicates
commands over the
IEEE bus but not
queries.
The terminator in the load may
not be matched to the
terminator of the computer
program being used.
Change the terminator in the load,
“ CR” (carriage return) or “ CR-LF”
(carriage return, line feed) using
the menu item 13 to match the
computer program being used.
Computer program used to run
the RS 232 is not properly set
up.
The computer program should be
set to 9600 Baud N8+1 (8 Bit, 1
Stop Bit, no parity).
Load does not
communicate over the
RS 232 bus.
RS 232 interconnect cable may
be loose or defective.
Tighten or replace the cable.