Melink Intelli-Hood Controls Reference Manual page 21

Operation/Service Specifications for Melink Intelli-Hood Operator
Change out optic "Y" cable at IOP. Preferably switch with a working optic channel in
o
order to ensure a good "Y" is being used. If a "Y" from a working optic channel is not
being used, try a second "Y" if the first one does not remedy the problem to reduce the
possibility that the replacement "Y" is bad.
APUs
•
Check cables using the "pigtail plug". Only pins one and two are used for the APUs.
•
Verify the 24 VDC signal is coming from the Autocal board.
•
Verify correct "Y" is being used. If a temperature "Y" has been substituted, the APUs will not work
correctly.
•
If APU runs but is noisy, check for interference from screws mounting the filter ring.
•
Replace as necessary.
Keypad
•
The 100% button can sometimes become stuck, causing the system to try and remain in bypass.
Try cycling the button to see if it will perform as expected. If not, replace keypad.
I/O Board
•
If seem to have fluctuating power on the system, check that all wire terminations are secure and
that input power is the correct voltage. Also check wire terminations between Autocal and I/O
boards.
Autocal Board
•
Since this is the "brains" of the system, a bad component can cause a variety of problems with
the system. If after performing previous checks the problem does not become apparent, then the
Autocal board is the most likely culprit.
When changing the Autocal board, stay grounded (use ground strap if available) to
protect board from electro-static discharge (ESD).
Single-phase to three-phase applications:
Problem: Existing single-phase motor starter still being used (utilizing drive to convert to three-phase)
and existing motor starter trips out even at low current draw.
Possible solution: The starter could be thinking that it is losing a phase. Try eliminating the existing
starter from the motor circuit and utilize an external run relay (can run off of existing coil). This way the
previous method of operation may continue to be used.
Drives:
Slowing Down Fan Speeds:
There may be occasions that require that the maximum speed may need to be adjusted. One example
would be converting a short-circuit hood to exhaust only (i.e. turning off MUA fan). To do this, reset the
maximum frequency (setting F03 on the GE drives) to the appropriate level. In order for the keypad to
display a full ten bars at maximum speed, the base frequency must be adjusted in the drive programming.
This will re-scale the control signals so that the fans will run at the appropriate speed throughout the full
range.
Note: Drives with covers (such as the GE/Fuji models) will run with the covers either on or off. However,
always power down the drive before installing or removing the cover. The only reason the drive should
be powered with the cover off is during troubleshooting, with extreme care being taken to ensure safe
practice is being used to protect personnel and hardware.
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