Scaling sensor data

If you are setting up scaling for an S-CIA or S-VIA analog input adapter with a sensor attached, refer to the sensor documentation for scaling values. For WattNode sensors, see Calculating energy in kWh and Calculating power in kW. See also Scaling factors for FlexSmart TRMS module and sensors and Scaling factors for the E50B2 power and energy meter. If you are using a Veris Industries H8051/H8053 kWh transducer, note that these devices provide a choice of “kWh per pulse” rate selectable with dip switches located on the transducer/CT. Make sure the scaling factors entered in these fields match your choice. If you do not have a multiplier and offset, you can calculate them using the raw output range and the corresponding measurement range as described in Calculating Multiplier and Offset for Smart Sensors.

Calculating multiplier and offset for smart sensors, wireless sensors, and water level sensors

You need both a multiplier and offset (also referred to as slope and intercept) to scale the data for a sensor. If the sensor documentation does not have this information, you can calculate them using the sensor's specifications for raw output range (raw values) and the corresponding measurement range (scaled values). You will need two raw values and their corresponding scaled values:

raw1 -> scaled1

raw2 -> scaled2

To calculate the multiplier (m), use the following equation:

m = (scaled2 − scaled1) / (raw2 − raw1)

If both raw1 and scaled1 are zero, calculate the multiplier using the following equation:

m = scaled2 / raw2.

In this case you do not need to enter an offset in the scaling configuration pane.

Once you have determined the multiplier, calculate the offset (b) using the following equation:

b = scaled1 − (m × raw1)

For example, you have a water level sensor that measures 0 to 10 feet, output as 4-20 mA to your device. In this case:

raw1 = 4 mA

raw2 = 20 mA

scaled1 = 0 feet

scaled2 = 10 feet

Therefore, the multiplier equation for this sensor is:

m = (10 − 0) / (20 − 4)

m = 0.625

and the offset equation is:

b = 0 − 0.625 × 4

b = −2.5

Some manufacturers provide their offsets in raw units so you must convert that value to scaled units (multiply by multiplier) using the following formula:

b (offset in scaled units) = m (slope) × offset in raw units.

Smart sensor scaling example 1: Counts to liters

In this example, counts are converted to liters to measure water usage during peak hours. Given a ratio of 1 count (raw1 value) equal to 5 liters (scaled1 value), the multiplier is 5 (5 / 1 = 5). The scaled units are liters, the scaled measurement type is Water Usage, and there is no offset. In addition, the sensor label should be "peak hours."

Smart sensor scaling example 2: Current to inches of water column

In this example, current in mA is converted to inches in water column (in WC) to measure air duct pressure. Assuming the following values:

raw1 = 4 mA

raw2 = 20 mA

scaled1 = 0 in WC

scaled2 = 10 in WC.

Therefore the multiplier calculation is: (10.0 − 0.0) / (20 − 4) = 0.625. The offset calculation is: 0 − (0.625 × 4) = −2.5. The scaled units are in WC, the scaled measurement type is Pressure, and the optional label is "air duct bldg 3."

Scaling factors for FlexSmart TRMS module and sensors

When configuring scaling for a FlexSmart TRMS (S-FS-TRMSA-D) module and associated sensors, use Table 3 to complete the fields. For your sensor model part number, enter the Scaled Units, Multiplier, Offset, and Scaled Measurement Type listed below in each of the fields.

**Table 3**. Multipliers to scale measurements.
Sensor Model	Scaled Units	Multiplier	Scaled Measurement Type
T-ACT-0750-020	Amp	0.0600006	Current
T-ACT-0750-050	Amp	0.1500015	Current
T-ACT-0750-100	Amp	0.300003	Current
T-ACT-0750-250	Amp	0.7500075	Current
T-MAG-0400-005	Amp	0.01501502	Current
T-MAG-0400-010	Amp	0.03003003	Current
T-MAG-0400-020	Amp	0.06006006	Current
T-MAG-0400-050	Amp	0.15015015	Current
T-MAG-0400-075	Amp	0.22522523	Current
T-MAG-SCT-005	Amp	0.01501502	Current
T-MAG-SCT-020	Amp	0.06006006	Current
T-MAG-SCT-050	Amp	0.15015015	Current
T-MAG-SCT-100	Amp	0.3003003	Current
T-MAG-SCT-200	Amp	0.6006006	Current
T-MAG-SCT-600	Amp	1.8018018	Current
T-MAG-SPT-150	VAC	0.34534535	Voltage
T-MAG-SPT-300	VAC	0.69069069	Voltage
T-MAG-SPT-600	VAC	1.38138138	Voltage

Scaling factors for the E50B2 power and energy meter

If you are using the E50B2 Power & Energy Meter (T-VER-E50B2), you can apply scaling to the Counts channel. Table 7‑4 lists the names and values you should enter in the Scaling fields. The default settings for the three native E50B2 data outputs are listed as well as all supported scaling values. These scaling factors must match the configuration entered into the device or you will find inaccuracies. Documentation on the E50B2 is available at www.onsetcomp.com/products/sensors/t-ver-e50b2.

**Table 7‑4**. Scaled units and multipliers measurement types.
For Scaled Units, enter this:	Choose a Multiplier to Enter:	For Scaled Measurement Type, enter this:
VARh	1 VARh per pulse (Default) 10 VARh per pulse 100 VARh per pulse 1,000 VARh per pulse 10,000 VARh per pulse	Reactive Energy
Wh	1 Wh per pulse (Default) 10 Wh per pulse 100 Wh per pulse 1,000 Wh per pulse 10,000 per pulse	Real Energy
Ah	0.001 Ah per pulse 0.01 Ah per pulse (Default) 0.1 Ah per pulse 1 Ah per pulse 10 Ah per pulse	Amp Hours

In addition to the three native data outputs (VARh, Wh, and Ah), you can also calculate other types of data outputs. To do this, download the CSV file and follow the instructions in the Microsoft Excel file located here: www.onsetcomp.com/resources/documentation/14993-derived-channels.

That file uses the following calculations for each additional type of data output, where 'h' is hours = Logging Interval / 3600:

Data Output	Unit	Calculation
Reactive Power	VAR	VARh/h
Volt-Amps	VA	SQRT (Wh^2 + VARh^2/h)
Volts	V	SQRT (Wh^2 + VARh^2)
Power Factor	PF	Wh/SQRT (Wh^2 + VARh^2)
True Power	W	Wh/h
True Power	KW	W/1000
Kilowatt Hours	KWh	Wh/1000
Amp	A	Ah/h