Lake Shore 648, Руководство пользователя

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2.5.3 Operation Under Field Control 15
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2.5.3 Operation Under
Field Control To obtain a linear field ramp, a magnetic sensor such as a Hall probe is placed in the
air gap along with the sample being tested. The sensor is connected to a gaussmeter.
The output of the gaussmeter is used to correct the programming input to the power
supply. In this way non-linearity can be corrected. Lakeshore manufactures probes
and gaussmeters for this purpose.
2.5.4 Avoiding Cooling
Water Condensation If the temperature of the cooling water is too cool relative to the air temperature and
humidity, condensation can occur. Condensation inside the power supply can cause
severe damage. To avoid condensation, the power supply operator must remain
cognizant of the ambient air temperature, cooling water temperature, and the
relative humidity. Lake Shore defines the limits of these conditions as follows:
D
ambient temperature = 18 - 28 °C (64 - 82 °F)
D
cooling water temperature = 15 - 25 °C (59 - 77 °F)
D
humidity = 20 - 80% (non-condensing).
Knowing the actual state of these conditions, the operator can calculate the dew
point, or temperature at which condensation will occur. TABLE 2-1 and TABLE 2-2 are
included to aid in dew point calculation.
Dew point calculation (in degrees Celsius)
% Relative Humidity
°C 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10
32 32 31 31 29 28 27 26 24 23 22 20 18 17 15 12 9 6 2 0
29 29 28 27 27 26 24 23 22 21 19 18 16 14 12 10 7 3 0 —
27 27 26 25 24 23 22 21 19 18 17 15 13 12 10 7 4 2 0 —
24 24 23 22 21 20 19 18 17 16 14 13 11 9 7 5 2 0 — —
21 21 20 19 18 17 16 15 14 13 12 10 8 7 4 3 0 — — —
18 18 17 17 16 15 14 13 12 10 9 7 6 4 2 0 — — — —
16 16 14 14 13 12 11 10 9 7 6 5 3 2 0 — — — — —
Dew point calculation (in degrees Fahrenheit)
% Relative Humidity
°F 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10
90 90 88 87 85 83 81 79 76 74 71 68 65 52 59 54 49 43 36 32
85 85 83 81 80 78 76 74 72 69 67 64 61 58 54 50 45 38 32 —
80 80 78 77 75 73 71 69 67 65 62 59 56 53 50 45 40 35 32 —
75 75 73 72 70 68 66 64 62 60 58 55 52 49 45 41 36 32 — —
70 70 68 67 65 63 61 59 57 55 53 50 47 44 40 37 32 — — —
65 65 63 62 60 59 57 55 53 50 48 45 42 40 36 32 — — — —
60 60 58 57 55 53 52 50 48 45 43 41 38 35 32 — — — — —
Example: Determine the actual air temperature and relative humidity. Find the
closest air temperature in the left-hand column and the closest relative humidity
across the top. If the air temperature is 24 °C (75 °F) and the relative humidity is 35%,
the intersection of the two shows a dew point of 7 °C (45 °F). Therefore, for the given
conditions, the cooling water must remain above 7 °C (45 °F) to prevent
condensation.
TABLE 2-1
TABLE 2-2