A few posts ago, I talked about Motor Controls while I was in Level 2 school at Red River College. I recently had the opportunity to apply the skills I learned on the job!

My job was to remove the “guts” from an old 600V motor controller, replace with new parts, and rewire.

Here is what the controller looked like immediately after it was removed from service. At the top is a 175A breaker. Bottom left is the contactor (also known as the coil). At the bottom right is the power transformer. Top right are the indication lights, and manual start/stop buttons.

Some quick explanations:

Contactor - Essentially a magnetic 600V switch that closes as required. The entire operation can be controlled automatically or manually. In this case, I am wiring the manual portion.

Transformer - Used to step down the system voltage from 600V to 120V, for the control circuit. In the above photo, the control circuit is shown with red wire; and the 600V circuit, with black wire.

Here is the controller gutted. (The transformer, indication lights and stop/start buttons are not removed.)

Pictured here are the replacement parts. (Left : 175A Breaker, Right : 600V Contactor)

Following the original print, I wired the circuit to specification. Using new wire, I wire checked, that is, followed the print and made sure my wiring matched it. Then, I tested the control circuit with 120V. When power is applied to the circuit, the green light (indicating “OFF”) is on. When start is pressed, the contact picks up. You can physically see the contactor pick up and hear it too. When you let go of the start button, the contactor stays picked up. The red light (indicating “ON”) is on. When stop is pressed, the contactor drops out, red light turns off and the green light is back on.

Here is the new and improved motor controller:

The winter season is upon us, and it’s time to turn the furnace back on. Hybord, the Hydro community where a lot of Grand Rapids workers reside, is made up of 30 houses, an apartment block, and a staffhouse. All these properties are owned by Manitoba Hydro, and they all contain electric heat. Therefore, it is the electricians job to perform tests to ensure the furnaces are operating properly.

We start by turning off the breaker. The furnace switch is flipped to “Winter mode”. The front panel cover is removed and the old filter is taken out. We vacuum the inside of the furnace and replace the filter. With the cover still removed, the breaker is turned back on. One person stays downstairs with the furnace, while the other heads upstairs to crank the thermostat. Using a clip-on ammeter, each element is measured for current draw as the thermostat continues to call for heat. We also make sure each element is turning on in the correct order.

This is what the elements look like:

The first two elements kick in while the fan is in it’s low stage. The remaining two elements kick in when the fan is in it’s medium stage.

Here is the current reading on one element. (20.91A).

When the elements are on, and the fan is in its medium stage, we clip the incoming power line. It should total approximately 85A if all of the elements are working properly.

The thermostat is returned to 15 degrees Celsius and the fan’s high stage is tested. This is done by flipping the furnace switch to “Summer mode”. The blower will operate at maximum speed.

Pictured below is the blower.

The furnace is flipped back to “Winter mode.” The cover is replaced and then we move onto the next house!

Our task this week is to perform two-year and four-year maintenance to a 230kV air blast breaker “R9.”

As found/as left tests

Before we start performing any maintenance on a piece of equipment, we perform “as found” tests. When we complete maintenance, we perform “as left” tests. This way, we know if while performing maintenance we affected the equipment in any way.

The testing on this particular breaker required work on the ground, and up at the top of the breaker. Rather than use a long extension ladder, we use a Genie manlift to reach the higher sections. Maneuvering the manlift takes extreme caution, as sharp movements (especially in the wrong direction) can be dangerous. Colliding with the stacks could cause the porcelain to break. When the breaker is in the open position, the stacks are full of pressurized air. It is especially important to avoid bumping the stacks to avoid a release of air.

One of the tests measures the time it takes each phase to open and close. The test equipment, called the “analyzer” is complex, but we are all trained on how to operate it properly. Connections are made at various points on the breaker, and connected back to the analyzer. We manually open and close the breaker, and the timing results are recorded onto a flash drive. Here I am pictured next to the analyzer.

Here I am standing with the analyzer.

Checking for air leaks

Air is the prime mover in this type of circuit breaker. A lot of equipment is designed to fail open. In other words, if there were a major problem with the breaker, it wouldn’t stay closed. It would fail in the open position, thus being safely de-energized.

The air for our switchyard of breakers is provided by a system of three air compressors. They are housed in the switchyard building, and are maintained regularly.

When this breaker opens, it fills the stacks with pressurized air. It is important that we don’t lose air to major leaks, as this causes a lot of wear and tear on our switchyard air compressors.

Pictured above is the control cabinet. The blue and yellow cards are “Test and Operate” cards. They are in place to allow the status of the valves they are hung on to be changed at any point in time while working on the equipment. This is one of the areas tested for air leaks, because there are so many air valves within.

Contact lubrication check

There aren’t many moving parts in this breaker, but the most important components are the main contacts. These move when the breaker opens and closes, and need to move freely. We remove both the contacts every four years to check for wear, and also for lubrication. Once they are reinstalled, we check to make sure the springs that help move the contacts are in good working order.

Pictured above is the breaker. The large grey tank at the bottom is the air vessel. The “M” shapes at the top are where the contacts and resistors are located. The columns are the stacks. Pictured at the far right is the current transformer.

Here is a closer view of the current transformer.

The generating station has it’s own fire protection system. It runs throughout the entire plant - and the pipes are easily identified by their red colouring. We maintain a system pressure of approximately 130 psi.

We test the operation of all three of our pumps weekly. Included in the test is recording the hour meter, and ensuring all the manual valves have not been operated. (This is accomplished by checking for the tags around the valves. If the tags aren’t broken, they haven’t been tampered with.) Most important in the test, is to ensure the pumps come on in the proper order, and at the correct pressure.

First in line is the jockey pump. It kicks on anytime the pressure in the system drops below 118 psi. If there was a fire, and the system pressure continued to drop, the jockey pump wouldn’t be able to maintain pressure. Second in line is the electric pump. It starts automatically when the pressure drops below 98 psi. If that isn’t able to keep system pressure up, our diesel pump starts. This kicks in at approximately 84 psi.

Jockey pump.

Electric pump.

Diesel pump.

An emergency situation is simulated to ensure each start point is reached. First the system drain valve is cracked open to start the jockey pump. Once the jockey pump gets the system back up to the correct pressure, we isolate it from the system. The drain valve is cracked again until the electric pump starts up. We let this run for 15 minutes, and watch for any leaks or smoke, listen for unusual sounds. The electric pump is then isolated. The drain valve is cracked once more until the diesel pump starts. This runs for 30 minutes. After 30 minutes is up, the RPM, the oil/water temperature and pressure, and battery amperage is recorded. The diesel has two backup batteries; both modes are tested.

After the test is completed, all pumps are returned into service.