The results of the various measurements of the input power and the output power are summarized in Table 1. The efficiency is defined as the ratio of the output power to the input power expressed in percent and the internal loss is defined as the difference between the input power and the output power. It should be noted that the efficiency and the internal losses are two related measures of the effectiveness of the device.

The two measured values of the input power were averaged to obtain the uncorrected efficiency data and the internal losses. In the remarks column in Table I, "Atten." indicates that the output measurement was made using the active attenuator, "TE" indicates that the output measurement was made using the thermal element and shunt, and "BI-200" indicates that the output measurement was made using the BI-200 load, in parallel with other resistors as necessary. The quantities "800 V" and "1000 V" are the nominal open circuit voltages of the battery pack. The entries in the column labeled "uncorrected efficiency data" are the ratios of the measured powers while the "corrected efficiency results" have been corrected for the known offsets. This column shows the estimated uncertainty of the measurements.

The corrections and uncertainties associated with these measurements are discussed in section 5. For convenience, the results of that discussion are summarized here. For the active attenuator, it is estimated that the true efficiency is within +/-4% of the measured value. The values measured using the thermal element are estimated to be 5+/-4% larger than the true value. Similarly, the values measured with the BI-200 load are about 10+/-6% larger than the true values. This means, for example, that if the value of the efficiency measured using the active attenuator is listed as 41% the true value is between 37% and 45%. If the value taken using the thermal element is listed as 54%, the true value is between 45% and 53%. Finally, if the value was measured as 77% using the BI-200 load, then the true value is between 61%

Figure 9

Schematic diagram of measurements using BI-200 load

Click on image to see larger version.

and 73%. No corrected efficiency is given for the two measurements made using the BI-200 as a load and the attenuator to measure the voltage across the load because no experimental data were taken to provide direct support for any corrections or uncertainty estimates. From other data and from a knowledge of the circuit, it is estimated that the uncertainty is no smaller than was obtained for the attenuator measurements using other loads and that the offset should be smaller than that obtained using the BI-200 alone. The variation of the efficiency under nominally identical conditions is greater than would be expected due to measurement uncertainty because, as was mentioned in section 2.2, the efficiency is not constant.

Load Resistor	Uncorrected Efficiency Data	Corrected Efficiency Results	Internal Losses
(Ohms)	(Percent)	(Percent)	(Watts)	REMARKS
400,000	29	29 +/- 4	2.5	Atten., 800 V
	30	30 +/- 4	2.5	Atten., 800 V
	34	29 +/- 4	2.4	TE, 800 V
	35	30 +/- 4	2.3	TE, 800 V
200,000	41	31 +/- 6	3.0	BI-200, 800 V
	39	29 +/- 6	3.9	BI-200, 800 V
	45	35 +/- 6	2.4	BI-200, 800 V
	44	34 +/- 6	2.4	BI-200, 800 V
	27	---	3.1	BI-200 + Atten., 800 V
	38	28 +/- 6	2.7	BI-200, 800 V
	27	27 +/- 4	3.0	Atten., 800 V
	39	29 +/- 6	2.5	BI-200, 800V
	27	27 +/- 4	3.0	Atten., 800 V
	45	35 +/- 6	2.6	BI-200, 800 V
	39	39 +/- 4	2.6	Atten., 800 V
	44	34 +/- 6	2.5	BI-200, 800 V
	39	39 +/- 4	2.7	Atten., 800 V
	45	40 +/- 4	2.3	TE, 800 V
	42	42 +/- 4	2.3	Atten., 800 V
	45	40 +/- 4	2.2	TE, 800 V
	42	42 +/- 4	2.3	Atten., 800 V
	35	30 +/- 4	2.5	TE, 800 V
	33	33 +/- 4	2.6	Atten., 800 V
	35	30 +/- 4	2.5	TE, 800 V
	33	33 +/- 4	2.6	Atten., 800 V
	41	31 +/- 6	2.6	BI-200, 800 V
	36	36 +/- 4	2.9	Atten., 800 V
	34	---	3.1	BI-200 + Atten., 800V
	45	35 +/- 6	2.4	BI-200, 800 V
	39	29 +/- 6	3.9	BI-200, 1000 V
	46	41 +/- 4	2.4	TE, 1000 V
	41	41 +/- 4	2.7	Atten., 1000 V
	45	40 +/- 4	2.5	TE, 1000 V
	40	40 +/- 4	2.7	Atten., 1000 V
150,000	44	34 +/- 6	3.0	BI-200, 800 V
	48	38 +/- 6	3.7	BI-200, 1000 V
	33	33 +/- 4	3.4	Atten., 1000 V
	37	32 +/- 4	3.2	TE, 1000 V
	32	32 +/- 4	3.3	Atten., 1000 V
	37	32 +/- 4	3.1	TE, 1000 V
100,000	54	49 +/- 4	2.3	TE, 800 V
	46	46 +/- 4	2.6	Atten., 800 V
	53	48 +/- 4	2.3	TE, 800 V
	46	46 +/- 4	2.6	Atten., 800 V
	52	47 +/- 4	2.7	TE, 1000 V
	50	50 +/- 4	3.0	Atten., 1000 V
	50	45 +/- 4	3.1-	TE, 1000 V
	47	47 +/- 4	3.1	Atten., 1000 V
50,000	53	53 +/- 4	3.1	Atten., 800 V
	55	50 +/- 4	3.0	TE, 800 V
	52	52 +/- 4	3.3	Atten., 800 V
	54	49 +/- 4	3.4	TE, 800 V
	50	50 +/- 4	3.2	Atten., 800 V
	54	49 +/- 4	3.1	TE, 800 V
	51	51 +/- 4	3.2	Atten., 800 V
	55	50 +/- 4	3.0	TE, 800 V
	59	59 +/- 4	2.6	Atten., 800 V
	63	58 +/- 4	2.4	TE, 800 V
	59	59 +/- 4	2.6	Atten., 800 V
	64	59 +/- 4	2.3	TE, 800 V
	53	53 +/- 4	3.0	Atten., 800 V
	59	54 +/- 4	2.7	TE, 800 V
	53	53 +/- 4	3.0	Atten., 800 V
	59	54 +/- 4	2.8	TE, 800 V
	59	59 +/- 4	2.6	Atten., 800 V
	64	59 +/- 4	2.4	TE, 800 V
	60	60 +/- 4	2.5	Atten., 800 V
	64	59 +/- 4	2.4	TE, 800 V
	40	40 +/- 4	4.9	Atten., 1000 V
	54	49 +/- 4	3.7	TE, 1000 V
	41	41 +/- 4	4.9	Atten., 1000 V
	55	50 +/- 4	3.6	TE, 1000 V
	73	63 +/- 6	2.9	BI-200, 800 V
	77	67 +/- 6	2.4	BI-200, 1000 V

When the 50,000-ohm load resistor was used with the BI-200, the load on the device was a parallel combination of the two systems. Therefore, the value of the load was 40,000 ohms during most of the cycle and 44,000 ohms when the commutator disconnected the ground from the coil without disconnecting the battery.