Model 1575e controllers are versatile and compact, and they can display various alarms based on how you set them up. This article outlines the alarms, what they mean, and what you can do about them. If you have a Model 140 (cooling tower) or Model 150 (boiler), the alarms are very similar.
How do you know you have an alarm?
- LED on the keypad – the red LED flashes when the controller sees any alarm condition
- Display – on your Process Screen, right under the system conductivity, any active alarm conditions will be displayed in a reversed out, flashing typeface. If there is more than one alarm occurring at the same time, the flashing alarm text will alternate between the multiple conditions.
- OnSight Notifications – If you have an OnSight Remote Access System set up, you can get alarm condition notifications for conductivity sent to your email or text. Other alarms will not be shared, however.
- Alarm Relay: You can set Relay 2, 3 or 4 as an alarm relay. It can be used to power a visible alarm (light stack) or audible alarm (bell, buzzer, klaxon). This relay will activate on ANY alarm, so be sure the relay is activating a light or audible device that is appropriate to the conditions.
What the alarms mean:
- High and Low Conductivity – easy! You set these limits in the Alarm screen from the main menu. When the system reads you are over or under these limits, the alarm condition is activated. Set your limits to indicate something is amiss – perhaps a manual valve is closed in the bleed line or there is a blockage preventing proper bleed/blowdown. Perhaps the makeup water conductivity is quite different from what you expected, and even with bleed/makeup occurring your conductivity is not dropping as you would expect. Or perhaps your conductivity sensor is not reading correctly – check it versus your handheld! Clean your sensor properly! Need a new sensor or bleed valve? We’ve got you covered and can ship in 1-2 days.
- No Flow: This alarm means that the controller is being told that there is no flow through the plumbing assembly. The flowswitch is comprised of a magnetic reed switch embedded in the plumbing assembly, and a magnet in the flow float. When flowing water (minimum 1GPM, maximum 5GPM) is present, the float is raised to where it will close the contact on the switch and tell the controller that there is sufficient flow to operate safely. When the no flow alarm is active there are several possibilities as to cause. Flow might have dropped below 1GPM. There could be a blockage downstream of the sensor that is preventing flow. It is possible that a valve either upstream or downstream of the plumbing assembly has been closed. It is also possible that the reed switch has failed. . Please call technical support with any questions about this alarm.
- Open TC or Shorted TC: Inside the 2-electrode cooling tower sensor is a small thermistor (TC). The thermistor changes value to coincide with temperature changes – because in a cooling tower the conductivity reading must be compensated for temperature of the water sample. This alarm means that the thermistor has failed, and you need to replace the conductivity sensor.
- Feed Sequence Active: This is more along the lines of a notification rather than an actual alarm. It means that a programmed feed schedule is active. This may be the pre-bleed, the actual feed, or the post feed lockdown. This notification is a normal operation of the feed schedule.
- Blowdown Timeout: Relay one has an option to set a blowdown timeout alarm. This will let you know if excessive blowdown is occurring past a time limit of your choosing. The alarm DOES NOT stop blowdown, but just gives a visual notification on the display on the alarm portion of the process screen.