CHAPTER 1: SYSTEM DESCRIPTION
875DP/500DP/500HV DUAL PULSE
RESISTANCE WELDING POWER SUPPLIES
1-2
990-290
Unitek Peco’s Schedule Protection feature protects Schedules from unauthorized or inadvertent changes.
One of its 16 schedules serves as a scratch-pad which anyone can use to perform occasional jobs without
jeopardizing the integrity of the production line. The exclusive Weld Fire Lockout feature guarantees that
weld quality is independent of line voltage fluctuations and the speed at which the power supply is operated.
Dual Pulse
Welding, an exclusive and unique feature of Unitek Peco power supplies, improves weld quality
and eliminates weld splash.
Dual Pulse
means each weld is performed with two pulses with independent
energy levels. The first pulse is used to displace the plating or contamination and reforms the surface so that
it is in intimate contact with the electrode. The second pulse welds the base metals. The Automatic Step
feature can be used to step to a new schedule, after a preset number of welds, in order to compensate for
electrode wear.
The 500DP, a modification of the 875DP, uses a different output transformer which provides 500 watt-
seconds. The 500HV provides 500 watt-seconds and uses an output transformer whose output voltage is
double that of the 500DP. The 500HV is frequently used in honeycomb welding and/or in those
applications which use handpieces whose cable lengths exceed 5 feet. Except for those specifications which
are directly related to energy rating and/or output pulse characteristics, the 500DP and 500HV are identical
to the 875DP.
The optional built-in Unitek Peco Weld Sentry adds a weld monitoring capability to the 875DP which
improves Process Control by detecting subtle changes in voltage, current, and power. The Remote Schedule
Feature allows the 875DP to reliably select weld schedules in automated applications. The 875DP can be
used with manual, user actuated, or air actuated weld heads.
The 875DP is a multi-voltage unit designed for operation at 100, 115, 208, or 230 VAC, 50/60 Hz.
Features
x
Multi-function, microprocessor control with 16 discrete weld schedules provides repeatable process
control and is compatible with air or manually actuated weld heads. Facilitates multiple applications at
a single work station and protects weld schedules from changes by unauthorized personnel.
x
Dual pulse welding eliminates weld splash. Improves weld quality especially when welding plated
materials.
x
Four weld functions are available:
¾
Basic
¾
Dual Pulse
¾
Rollspot (seam weld)
¾
Sequence Repeat