Watlow QPAC Modular SCR Power Control Service - Manual (Page 6)

6
WATLOW QPAC Service Manual
Overview, Chapter 1
Specifications
QPAC Specifications
Operation
• Modular control base with plug-in card and transformer
• Plug-in control cards
• Solid state contactor, AC or DC input
• Burst firing (zero cross) control, fixed or variable time base
• Phase angle control with soft start and current limiting, or digital input
• Plug-in transformers (50/60Hz)
• 120 VAC operation
• 208/240 VAC operation
• 380 VAC operation
• 415 VAC operation
• 480 VAC operation
• 600 VAC operation, consult factory
• Power bases
• Single phase (Q01), 1 pair of SCRs
• Three phase (Q32), 2 leg control, 2 pair SCRs.
Resistive load only, balanced or unbalanced, burst firing (zero cross) only
• Three phase (Q33), 3 pair hybrid SCRs/diodes
Recommended for phase angle only with balanced load.
Control Cards
• (QCA) Solid state contactor, AC Input (08-5285)
• 120 VAC @ 30mA minimum
• AC signal input sources (ie., Triacs or mechanical relay outputs with noise
suppression) require customer supplied resistors across the power control
AC command signal input terminals to prevent false firing.
• 24 VAC input, 200
Ω
/10 watts typical
• 120 VAC input, 1K
Ω
/25 watts typical
• 240VAC input, two 1K
Ω
/25 watts in series typical
• (QCD) Solid state contactor, DC Input (08-5286)
• ON, 4 to 10VDC; OFF, 0VDC
• Built-in noise reduction network
• (QBF) Burst firing (zero cross) control Fixed Time Base (08-5289)
• Process input factory set @ 4-20mA
• Input impedance 250
Ω
(clip resistor for 5K
Ω
voltage input)
• Time Base 4 seconds (clip resistor for 1 sec)
• (QBV) Burst firing (zero cross) control , Variable Time Base (08-5342)
• Process input factory set @ 4-20mA
• Input impedance 250
Ω
(clip resistor for 5K
Ω
voltage input)
• Bias and Gain card optional
• (QAF) Phase angle control (08-5288)
• Process input factory set @ 4-20mA
• Input impedance 250
Ω
(clip resistor for 5K
Ω
voltage input)
• Soft start 10 sec (approximately)
• (QAL) Phase angle control with current limit: (08-5411)
Some heater elements change resistance during their operation, (i.e., silicon
carbide). In order to control at a slow ramp, it is often advantageous to limit the
current. Sensing the current is via a current transformer. This is NOT a means
of protecting the SCR.
• Process input factory set @ 4-20mA
• Input impedance 250
Ω
(move jumper for 5K
Ω
voltage input)
• Soft start 10 sec (approximately)
• Current transformer included
• Current Limiting.
• (QAD) Phase angle control with digital input (08-5314)
• Remote digital phase control
• Interface, Centronics® parallel, 8 lines
• Power steps, 256