TDI-Dynaload Division
WCL488 Series Water Cooled Electronic Loads
Operation & Programming Manual
402828, Rev. B1
Page 25
Category
Fault Indicator
Description
UV — Undervoltage
DC ON will not function until voltage is greater than 0.4
Volts (override switch provided on rear panel). See the
Undervoltage Lockout
section below.
OV — Overvoltage
Unit will disconnect from source.
Major
Faults
OT - Overtemperature Unit will shut down.
OC — Overcurrent
Unit has reached the set current limit or the current limit
of the selected range.
OP — Overpower
Unit has reached the set power limit.
SAT — Saturation
Saturation condition whereby one or more of the
electronic power components are completely saturated.
This may be due to insufficient source voltage,
inadequate wiring, or excessive line loss. This may also
indicate an open power device.
Minor
Faults
MOD — Module
Indicates that there is an abnormal operating condition
at the module level.
Undervoltage Lockout
The UV switch on the rear panel has two positions, ON and OFF. When the switch is ON, the DC
relay will not engage and the SYS and UV fault indicators will be on until there is greater than
0.4 volts applied to the DC inputs. Anytime the voltage drops below 0.4 volts the relays will
disengage and the UV alarm will be latched. Please note that the DC relays will re-engage and the
SYS fault LED will extinguish when the input voltage goes over 0.4 volts, but the UV fault
indication remains until cleared with the LOAD ON command over the IEEE bus or by
depressing the DC ON button on the front panel. When the UV switch is in the OFF position this
action is inhibited allowing for load operation under 0.4 volts.
This function is separate and distinct from the programmable undervoltage function.
Programmable Under Voltage
In addition to the Undervoltage Lockout, the load also has a Programmable Under Voltage
feature. This feature provides a means to have the load automatically stop loading when the input
voltage from the device under test drops below the defined threshold.
Unlike the Undervoltage Lockout, the Programmable Under Voltage can be set to generate a fault
when the Voltage drops below its defined Voltage. The Voltage level can be programmed
through menu item #18 or the through the IEEE 488 (or RS232) interface using the UV
command. Like the hardware Undervoltage Lockout, this will open the load connect relay and
generate a UV fault. Other than its programmability, it differs from the Undervoltage Lockout in
that once the input voltage has dropped below the Programmable Under Voltage threshold
causing a UV fault; the load will not re-connect until a DC LOAD ON is commanded. For this
reason the input Voltage must be above the Programmable Under Voltage setting before
performing a DC LOAD ON. Otherwise a UV fault will occur immediately and the DC LOAD