Page 124 • 700120S • ENTRON Controls, LLC.
9.7.2 VALVE 2 (Magnetic Isolation Contactor Output CR1)
This Magnetic Contactor’s function is to isolate the Welding Transformer from the control in
the possible case that the weld control should malfunction. For example, an SCR could fail
shorted during the time the part was being held and maximum current could flow.
Program same desired schedule using Valve 2 for SQUEEZE, WELD, and HOLD times (set
VALVE MODE=
0303
0303
03). This valve (if programmed) will stay on only during the weld sequence
(SQUEEZE, WELD, and HOLD). The Isolation Contactor can be supplied from the factory at
time of order. Contact ENTRON for further information.
Valves 1-3 can only sink 1 amp of current. Check Isolation Contactor current draw. If current
is too high, use a Relay (CR1) to buffer the Isolation Contactor as shown in Figure 9-17.
ALSO
Be certain Valve Transformer or Power Source at VL1 and VL2 can supply sufficient power
for Valve 1, Isolation Contactor, and Alarm Relay.
THE ISOLATION CONTACTOR MUST BE CONTROLLED BY VALVE 2 SO THE
WELD TRANSFORMER IS ISOLATED FROM THE WELD CONTROL
WHEN PART
IS HELD IN WELDER.
IF ISOLATION CONTACTOR IS NOT USED, UNCONTROLLED WELD CURRENT MAY
BE APPLIED TO HELD PART.
This is REQUIRED as the Control Relays in the weld control will be held in the ON state
until the part is removed
or SCRs can fail in shorted condition (see Figure 9-17).
9.7.3 VALVE 3 (Alarm Output CR2)
Valve 3 will turn on while part is being held in welder, for currents either over the HIGH limit
or below the LOW limit. This output can be used to light a signal lamp or give error indication
to a PLC.
When HIGH or LOW ERROR is present, Valve 1 (Welding Head Solenoid Output) and Valve
3 (Alarm Output) will stay on until the error is cleared by pressing any Front Panel button or, on
weld controls with a Program Lockout key switch, the key must be rotated and the error cleared
before the part can be removed from the welder. Valve 2 (Magnetic Isolation Contactor Output)
will turn off at the end of HOLD time, removing power from the Weld Transformer. When the
error is cleared, all valve outputs will turn off and the control will go through a Power On Reset.
WARNING
NOTICE
To Next Page
Loading...
