THE INHERENT PROTECTOR

Suppose you are testing a Copeland 3D (Discus) compressor and your ohmmeter registers OL from line to line on all of the 3-phase legs. The compressor is cold so you determine that the compressor is not off due to an overheat/internal thermostat trip. Your early assessment is that the compressor is bad and must be replaced. You call your supervisor who immediately sees a red flag when you say all 3 windings are open. It may be a defective “inherent protector”. This happened to a service tech that I supervised a few years ago. And it did have a bad protector.  Please see the following photo and wiring diagram for more information on how this all works and the numbers needed to obtain a replacement inherent protector. By the way, this part is located beneath the terminal plate and is mounted just above the motor windings in order to detect the first possible overheat situation.


MIDDLE TN RSES TO HOST HVACR CONTROLS COURSE

Get ready Nashville for the much anticipated and most requested HVACR training experience.

Continue to monitor this website for information regarding registration for this seminar.


DANFOSS WINS PRODUCT OF THE YEAR AWARD AT 2018 AHR EXPO

Danfoss, the pioneer of oil-free, magnetic bearing, variable speed technology, was recognized with the prestigious Product of the Year award during the 2018 AHR Expo for its Danfoss Turbocor® TTH/TGH high-lift compressors. 

A GAME-CHANGING APP

I just can’t say enough about an app that has become an essential part of my life and the overall operation of our HVACR service team.

I am talking about EVERNOTE. It is one of the best ways to assemble, organize and present information that I have ever seen. Now you may be thinking that I am compensated for endorsing this product but you are wrong. I am compensated by using the product. I use it for training purposes as well. It has a great presentation mode that I use instead of powerpoint slides.

I use it many times per day. It is extremely useful when we have our weekly service huddle meeting.

Below is a screenshot sampling one of our huddle meeting frameworks.

You can easily hyperlink the topics to other notes that have been organized into specific Notebooks.

We also have the essential Notebooks shared with all the service techs. It is feature-rich and the beauty is that it syncs across just about all platforms.

An example list of our company shared Notebooks contain the following topics: Work Data, Parts Information, Site Information, Memos, Policies, Training, etc. In these Notebooks are contained over 500 notes and training presentations. It is easily searchable for specific notes inside these Notebooks.

As we go throughout the week and run across some useful topic to discuss or encounter a recurring issue, we add it to the list for “Monday” and we keep the team informed. It helps us to maintain a near-paperless approach to our day to day business practices. For all our larger digital files that contain operation manuals and other manufacturer information, we use Box, which contains over 12GB of technical information for our team to access.

My wife and I both have the premium version and use it for all our financial paperwork and household business. Click here to for a free trial of Evernote.

TESTING AIR FLOW IN SUPERMARKET CASES

One of the ways to assure that a customer’s case is performing as it should is to test the airflow. One of the best ways to do this is with a test instrument that measures feet per minute as illustrated.

Be sure to measure the airflow at the case discharge air outlet as illustrated below:

The manufacturer recommends that the best time to measure the case airflow is during the warmest time during defrost as the case cycle is terminating.

Below is a manufacturers chart detailing an example of a case specifications including the case design average air flow. Without the proper air flow, the case temperature will not reach the desired set point and the product integrity will suffer.


HANDS-ON COMPRESSOR TRAINING AT MIDDLE TN RSES

Members and guests got to check a fractional hp compressor for good/bad windings at the June 2017 Regular Monthly Meeting at the Middle TN Chapter. Jayson Goff, CMS was the seminar leader and had just returned from a winning battle over Stage 4 cancer. By the way, the compressor was deemed terminally ill by Larry Lynn, CMS and Doug Drake, CM, due to bad terminals.  😀

Indoor Air Quality Begins Here

The final factor in evaluating the air distribution in a space is the comfort of the occupants. In general, a person is thermally comfortable when body heat loss equals body heat production. What most people call a “draft” is simply a slight movement of air that results in a local feeling of “coolness.” It has been determined that a velocity change of 15 ft/min has about the same effect on comfort as a 1°F of temperature change. KEEP READING BELOW…..

A typical room air distribution system with local air velocities of less than 40 to 80 ft/min will satisfy 80% of occupants. Localized air temperatures should be less than 2°F below the general room temperature. The temperature near the floor should be less than 4°F below that at about shoulder height. For heating, local air velocities generally are below 40 ft/min. For cooling, local air velocities should be between 40 and 80 ft/min.

EXCERPT FROM “THE TECHNICAL INSTITUTE MANUALS,” available from the ONLINE STORE AT RSES.ORG

Sheave Maintenance

Routine maintenance of blower sheaves should include a close examination of the alignment of the motor and blower sheaves. Proper belt tension is also important to maintain the life of the sheaves. Groove gauges are often provided by belt and sheave suppliers to test the sheave walls for wear to determine the need for replacement.

Another important item to check is the RPM’s of the blower to determine if it is within the range that was established during commissioning by test and balance personnel or startup technicians. Once the sheaves get a measurable amount of wear, it becomes increasingly difficult to provide the proper air delivery of the blower due to lost RPM’s.

VIBRATION ELIMINATORS

Rigid connections at the compressor are prone to crack or break from vibration and stress. The cause may be discharge gas pulsation or compressor movement because of high torque.

There is a simple way to prevent line breakage from these causes. Install vibration eliminators in both the suction and discharge lines. They should be the same size as the lines. Install the vibration eliminators parallel with the drive shaft on the compressor. It should only be clamped on one end.

A typical vibration eliminator has rigid copper ends to connect to the compressor and the system. Between the ends is a length of flexible tubing. It is covered with woven brass or stainless steel mesh for strength.

EXCERPT FROM THE TECHNICAL INSTITUTE MANUALS AT THE ONLINE STORE OF RSES, THE HVACR TRAINING AUTHORITY.

THE BASIC RELAY

Relays are electrically operated control switches, and may be classified as either power relays or control relays, according to their use. Power relays are frequently called contactors. Control relays are usually known simply as relays.

As you can see in this illustration, there are four basic parts to the relay. The coil of wire becomes magnetized when a voltage or current is applied to it. The armature is connected to the contacts. (Generally, the armature and the contacts are electrically isolated from one another.) The spring keeps the relay in its normally open or normally closed position when no power is applied.

Excerpt from “Electricity for HVACR Technicians“, available from the online store at RSES.ORG.