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General Guideline:
• Q-Controller uses half-wave rectifier only
• Q5 TB5 is half-wave rectifier
• Q8 TB6 is half-wave rectifier
• All I/O boxes are half-wave rectifier
• It is okay to connect multiple devices to the same AC transformer and share signal
commons if
o Every device uses a half-wave rectifier
o And the same AC lead on every device is used for common
• If the power supply is 24VAC, no matter it is GROUNDED (one side of AC is
connected to ground), or FLOATING (neither side of AC is connected to ground),
the polarization is important, make sure the Neutral or the same AC lead is
connected to the GND of TB10. Make sure the same AC lead is connected to
ground in all devices that share the AC source. Treat AC like DC for purposes of
watching polarity in this case.
o For Q5, the TB5 of Q5 can only be connected to the same AC source
o For Q8, the TB6 of Q8 can only be connected to the same AC source
o For I/O boxes, they can be directly connected to the same AC source
o For other devices, only the device with half-wave rectifier can be
connected to the same AC source. If it doesn't have, or any doubt exists,
provide a dedicated isolated transformer to the device
• If the power supply is 24VDC, all the devices can be powered by the same DC
source.
• Whenever you have different devices from different manufacturers, be careful to
separate those devices that utilize a Full-wave rectifier from those using a Half-
wave rectifier. When any doubt exists, provide a separate transformer. The small
expense of an additional transformer or two will more than make up for all of the
time and money spent on troubleshooting
• Please refer to Q-Controller Installation Drawing for power & RS-485 Connection
• It is necessary to bear in mind the actual installation when sizing the transformer.
The installation requirements can run theoretically from only 15 VA to over 200
VA. These systems ranging from a single controller, a few electrochemical
sensors to a full 128 Combustible sensors with several remote relay modules.
• It is always best to allow some safety margin in designing power supplies, and
25% to 50% allowance for startup surges and future requirements is
recommended.
QEL supplies one standard transformer
M-Transformer
Q-Controller System Operation Manual
86550-001-000 Rev B
120 to 24 VAC 200 VA
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