Watlow QPAC Modular SCR Power Control Service - Manual (Page 5)

WATLOW QPAC Service Manual
5 Overview, Chapter 1
Overview
Control Cards Part Number
• Solid state contactor, AC input, QCA 08-5285
• Solid state contactor, DC input, QCD 08-5286
• Burst firing (zero cross) fixed time base, QBF 08-5289
• Burst firing (zero cross) variable time base, QBV 08-5342
• Phase angle control, QAF *
08-5288
• Phase angle control with current limiting, QAL * 08-5411
• Phase angle control with digital input, QAD *
08-5314
* For 1Ø & 3Ø, 3-wire controls only; not for 3Ø, 2-leg controls
Plug-in transformers (50/60 Hz)
Part Number
• 120VAC 16-0200
• 208/240VAC 16-0201
• 277 16-0202
• 380VAC 16-0208
• 415VAC 16-0207
• 480VAC 16-0203
• 600VAC 16-0209
(consult factory)
Power Bases
with Motherboards
• QPAC-01:
1Ø, 30 to 300A
• QPAC-32:
3Ø, 2-leg, 30 to 300A
• QPAC-33:
3Ø, 3-leg, 30 to 300A
Figure 2 -
QPAC Modularity
Overview
Q01 is a single phase power control that operates with any type of firing method
such as burst fired, phase angle, variable time base, and AC. It uses a pair of
back-to-back SCRs (“package” or individual) depending on amperage ratio.
Q32 is a 3-phase, 2-leg power control that can operate on most types of firing
methods, except phase angle, and controls two of the three legs. The QPAC-32
was designed for zero cross applications only. It uses two pairs of SCRs, individ-
ual or SCR package, depending on amperage ratio.
Q33 in a 3-phase, 3-wire hybrid (SCR and diode) power control that operates with any
type of firing method. It features a series of jumpers for fast AC input changes after
changing transformers, and a jumper for changing from burst fired to phase angle fir-
ing. It also has LEDs to indicate “Power On,” “Phase Lock Loop,” “Phase Rotation,”
and “Phase Loss.” For fast malfunction diagnostics, and for bench troubleshooting,
complete data is on the board at a series of test points. Integrated circuits are easy to
change by simply plugging and unplugging for replacement or testing.
Indications of Malfunction
1. No output under any circumstances.
2. Full ON output at all times and the load is uncontrollable.
3. Output is not proportional to the command signal (unbalanced output).
4. Operating erratic and inconsistent.
5. Half output.
6. One or more LEDs not lit on the Q33 base
SCRs Part Numbers
Unit QPAC-01 &
Rating Q-PAC-32 Q-PAC-33
• 30A 18-4013 (*1) 18-5179 (*1)
• 50A 18-4013 (*1) 18-5179 (*1)
• 75A 18-4013 (*1) 18-5179 (*1)
• 100A 18-4015 (*1) 18-5179 (*1)
• 150A 18-5052 (*2) (*NOTE 3)
• 200A 18-5052 (*2) (*NOTE 3)
• 300A 18-5052 (*2) (*NOTE 3)
(*1) SCR Type: Module.
Torque 40"/LB
(*2) SCR Type: 3/4" Stud.
Torque 280-300"/LB.
(*3) SCR: 18-5052.
Diode 18-1044.