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When to plug heaters in or unplug them
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Author:  GeneralQuestion [ January 15th, 2013, 9:47 am ]
Post subject:  When to plug heaters in or unplug them

I have been given conflicting advice on when to plug the heaters in the fusion machines. People on all sides say that doing this wrong burns up the boards (PCB) in the heater. People are very adamant about it and everyone says that "McElroy says to do it this way." Some say I should do it before I start the machine. Some say I should do it one the machine is in high idle. While others say start the machine, plug the heater in and then go to high idle. I have heard all manner of rationales for each method and am thoroughly confused.

So the million dollar question is: What does McElroy really say?

Author:  Joshua [ January 15th, 2013, 10:03 am ]
Post subject:  Re: When to plug heaters in or unplug them

I too have heard a lot of discussion on this. I talked with engineering and here is what I can tell you that is based on facts not people's opinions. (including my own)

McElroy did some testing on the boards. They changed the frequency as well as the voltage to see if we could find any potential issues. The tests were conducted on REV D and E boards. I can post the write up detailing some of the testing but here is the skinny.

Our position is that for McElroy heaters being plugged into McElroy machines, it doesn’t matter if the engine is running or what the rpm’s are when plugging the heater in or unplugging it.

That is from our design group.

Author:  dale stafford [ January 15th, 2013, 2:15 pm ]
Post subject:  Re: When to plug heaters in or unplug them

From my experience and alot of tracking on each piece of equipment if you shut down a generator with an iron plugged in there's a chance the heating element could burn out or visa versa breaker should be shut off it will prolong the life of heating elements though I never heard of a board burning out have approx 200 irons in three years only replaced 3 boards. Since the men been unplugging irons from generator or shutting off breaker replacement of heating elements went down 85% Thats A Fact 3year survey.

Author:  mikee [ January 30th, 2013, 1:26 pm ]
Post subject:  Re: When to plug heaters in or unplug them

of course it makes a difference. voltage is set with engine speed. plug in prior to starting you risk overvolt situation if governor on engine fails to fuction properly. Same on shut down, will undervolt as engine speed drops. On T500 you will burn the pins up on heater plug if you connect/disconnect with engine running on high speed.
and yes things are much better now (D-E-F boards) then in the past.

Author:  Joshua [ November 11th, 2013, 5:23 pm ]
Post subject:  Re: When to plug heaters in or unplug them

Heater Control Board Low Voltage Test

Object: Determine if McElroy heater control boards are damaged if plugged into a machine while it is at low throttle.

Performed: 9/29/11

Units under test:
Heater Control Board Assembly T5030001 Rev. D, (4 each)
Heater Control Board Assembly T5030001 Rev. E, (1 each)

Equipment used:
Variac variable autotransformer
Fluke #187 multimeter
Fluke #87 multimeter
#14 heater
#28 heater
TracStar 28

Test #1 - Voltage Variation

1. Wire heater board to the #14 heater.
2. Power heater/board from the Variac.
3. Set Variac output to 120 volts.
4. Verify board is functional.
5. Lower Variac output until controller goes into error state, (red LED flashes rapidly).
6. Turn Variac down to zero volts to reset the heater controller.
7. Increase Variac output to 50 volts. Verify heater controller functions properly.
8. Increase Variac output 10 volts every 10 seconds until the 120 volts is reached. Verified the board functions at each increment.
9. Repeat steps 1 thru 8 with remaining heater control boards.

The results were the same for all heater control boards. They were verified functional at initial power-up. Each went into an error state at about 32 volts. They all returned to proper condition when power was cycled. Each functioned properly at every increment between 50 and 120 volts. Note: The heater controller’s output relay would not close (no power to heater elements) when supply was less than 70 volts.

Test #2 - Frequency Variation

1. Run TracStar 28 at low throttle.
2. Plug heater into 120 volt receptacle.
3. Measure voltage at 240 volt receptacle.
4. Adjust throttle until output at 240 volt receptacle is 160 volts.
5. Measure frequency of generator output.
6. Repeat Steps 4 & 5 at 20 volt increments from 160 to 240.
7. Change throttle setting from minimum to maximum 5 times.

The heater control board functioned properly throughout the test. The following chart shows the voltage and frequency variation due to engine speed.

Voltage at 240V Receptacle Voltage at 120V Receptacle Frequency
160 VAC ~80 VAC 47.3 Hz
180 VAC ~90 VAC 49.9 Hz
200 VAC ~100 VAC 52.7 Hz
220 VAC ~110 VAC 55.6 Hz
240 VAC ~120 VAC 58.7 Hz

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