Global 1120, Руководство по эксплуатации

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Global Power Technologies
1120 - Class I, Division 2, Group D, T3
1 .5 Electrical Output Characteristics
Figure 3 shows the electrical output characteristics of the Model 1120 power unit, which gives
the power, current and voltage as a function of the load resistance. The TEG will operate at
any load condition from short circuit to open circuit. Observe that the power goes through a
broad maximum between 0.3 and 0.5 ohms. Rated power (120 Watts) can be obtained only
if the load resistance is within this range. The graph is useful in determining power, current
and voltage at various customer load conditions. Refer to the graph and consider the following
example:
1) You are installing a Model 1120 TEG at a gas wellhead to cathodically protect the
well-casing from corrosion.
2) You have measured and determined your total ground bed resistance to be 1.0 ohm.
3) Find 1.0 ohm on the horizontal axis.
4) Read vertically until intersecting the power, current, and voltage curves.
5) Read horizontally to the vertical axis to determine the values of power, current and volt-
age.
6) Which are 106 Watts, 10.2 Amps and 10.3 Volts.
1.6 Ambient Temperature Effects
The electrical output of the TEG is dependent on ambient temperature as shown in Figure 4.
Observe that the power decreases as ambient temperature increases.
Statement of Rated Power
1) The Power Unit produces 120 Watts when operated at an ambient temperature of 20ºC.
2) With the fuel flow held constant, the power changes at a rate of 0.288% per ºC (0.16% per
ºF) of temperature change.
3) The TEG can be operated at rated power to a maximum ambient temperature of 40ºC
(105ºF). Consult GPT if ambient temperatures exceed 40ºC.
1 .7 Rated Power
The TEG can be adjusted for rated power at an ambient temperature by using the rated power
curve as shown in Figure 4. Consider the following example:
1) The present site temperature is 40ºC.
2) Find 40ºC on the horizontal axis.
3) Read vertically until intersecting the rated power curve.
4) Read horizontally to the vertical axis to find the set-up power.
5) Which is 114 watts.
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