Specifications

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Page 49

Geolograph hookup

not working right

This is due to an electrical or mechanical problem which may need adjusents to

remove. Register 25 is the debounce register. Adjusting it will eliminate the multiple

bouncing of the microswitch within reason. There are two sources as to excess depth

counts.

Mechanical Contact Bounce: when the arm of the geolograph contacts or releases

the switch, the switch moves into the open or closed mode. When it does, the contacts

bounce on and off inside the switch itself. Register 25 will eliminate these multiple

strikes if even set to 1 second, because contact bounce lasts only milliseconds.

Mechanical Switch Bounce: if the mechanical geolograph arm is constantly

bouncing up and down due to wind, chatter, or a faulty or loose mechanism, it can

cause multiple hits on the microswitch. Register 25 can be set to a higher number,

such as 60 seconds or more, to counter this problem. Another way to counter this

problem is to use a depth wheel from US Geosupply with one of our corrective PC

boards in it. This device connects to the geolograph cable and counts depth in only

one direction.

Electrical Induced Noise: when the geolograph cable is placed over large power

lines, especially when in the same power conduit running under roadways, a single

twisted pair cable will have induced noise on it. Sometimes this noise can reach as

high as 80 volts AC. The Bloodhound system uses an electrically isolated geolograph

input in order to protect the Bloodhound system from this induced voltage, but it can

not cancel the noise on the geolograph line. In this case the Bloodhound will usually

give a noisy geolograph alarm.

Electrical Ground Potential Noise: when the trailer holding the Bloodhound is at a

great ground potential relative to the drilling rig, an induced DC reference can be

generated on the geolograph line. In both cases, to eliminate the noise, try the

following steps:

 If you are not running CAT 5E cable for the geolograph, go get some.

 Run CAT 5E Network Cable. This cable has a high twist to it which helps eliminate

the induced noise.

 Run CAT 5E Shielded Network Cable. This cable has an additional conductive

shield that helps eliminate induced noise.

 There are 8 conductors in CAT 5E. You are probably using 2 for the geolograph

cable. Strip back the other 6 and the shield wire, if it has a shield, tie them all

together and connect them to the black 12VDC screw terminal power lead on the

same side of the Bloodhound. This will reference the geolograph line to the

Bloodhound ground reference and eliminate the noise. Do not connect the far end

of the 6 cables and or shield wire to anything. (If you do so, you do not have a

shield, you just have another ground line and that will not help you.)

 If you are using a 2 conductor wire, strip back and tie a small piece of wire from the

black geolograph terminal to the black 12VDC power lead. At least you will have a

common ground reference in the case of induced noise.

Span adjusent

unsuccessful

When adjusting the zero and span on a particular gas, always adjust the zero first,

then the span. Adjusting the span first and then zero will throw off the span adjusent.

Oxgen sensor drifts

This sensor was included as a differential monitor as to the amount of methane in the

sample. If user observes 5% of methane then the O

should change about 1% no

matter where it is presently.

It is very sensitive to back pressure, and is sensitive to chemicals that may be

encountered in the drilling process. One of the most reactive is acetylene which may

be generated using carbide for a lag check. Acetylene may knock the oxygen sensor

out for up to 20 minutes. Because of these cross reactions, it is not immune to drift

and should be adjusted to 21% periodically to air. To do this just disconnect the

sample line for a few of minutes and adjust to 21%.