CSZ EZT-570i, Техническое руководство

Страница: 5 / 95

EZT-570i Technical Manual
5
2. Where Do I Begin?
The EZT-570i is a Distributed Control System (DCS) that uses different hardware layers to perform
the various functions needed to operate the chamber. These include the user interface (HMI), the
control module (CM) which handles system monitoring and protection, as well as process control
(9300 controllers). This type of platform distributes the work load of controlling the chamber into
different devices and allows us to break the system down into these layers for troubleshooting which
makes diagnosing problems quicker.
Instead of looking at the system as a whole, look at each component and focus on what task it is
performing and whether or not it is doing it right. Start from the component level when tracing a
problem and work backwards from what is not working. Some problems are obvious. If I am trying to
enter a set point and the touch screen is not responding to my touch, then it is a problem with the
HMI. However, when the chamber is not doing something it is supposed to, is it the controller or
something else? Over 90% of the time it can be attributed to a wiring fault or single component
failure that prevents the system from operating. It isn’t the controller.
Example: The chamber is at 75°F and the set point is 185°F. The fans are running, but it is not
heating up. What is wrong?
Instead of approaching the problem by assuming the controller is not calling for heat, ask
why is the chamber not heating up? Are the heaters on? Using the electrical schematic
for the chamber, locate the power wiring for the heater. Is there voltage to the heaters?
Is the heat output of the controller on, i.e., is the solid state relay on to supply power to
the heater. Is the heater contactor on? Is there a blown fuse?
Start from the heaters and work back. This will allow you to find what is not allowing
power to pass to the heaters. It may even be several components, like the contactor and
solid state relay, both of which get power from a common wire that may be shorted or
open due to a limit device which needs to be manually reset.
The EZT performs the same function on the chamber as any other controller. It has heat and cool
outputs for controlling temperature based on a set point. It has humidify and dehumidify outputs to
control humidity based on a set point. These outputs control the same heaters, compressors and
solenoids that any other controller would.
Since the EZT has a host of additional features and more functionality than other controllers, it is not
uncommon to look inward on the controller and blame it for any problems that arise. However,
software does not change. If it worked yesterday, then it is working today. What may not be working
is a valve that reached then end of its cycle life or a wire that has come loose or corroded to a point
where it will no longer pass power. Those types of failures are far more common.
An alarm condition may be present and not indicated on the EZT if a hardware failure or
wiring problem exists. Keep this in mind when there are no obvious fault conditions present
that would indicate why the chamber is not working properly.
In order to begin troubleshooting an issue, narrow down the search by determining which section of
this guide the problem most likely falls into based on the following information.