# Week12 : Group assignment

### Group Assignment

group assignment:
measure the power consumption of an output device

## Instruments

Cartridge heater

### Measuring tools:

• DC Power supply1
• Tester
• Thermometer (Thermocouple)
Made by Daisuke Doyo on week11 assignment

## Testing resistance of the device

To roughly grasp the number, we first measured the resistance of the device, so that we can know how much current will flow into the circuit at the maximum voltage.
The DC power supply can supply up to 2.5A in 0 to 30V range.

The resistance of the heater was 183.6Ω.
This means when we put 30V, which is the maximum voltage that DC power supply can serve, 163mA of current will flow into the circuit. This is within the range of capacity that our power supply can serve. Great.

## Test setup

We measured the temperature of the heater and the current at each 5V / 10V / 20V / 30V point.
Apply voltage with DC power supply, measure current with a tester, and temperature with Daisuke’s thermometer.

## Result

The horizontal axis implies Voltage and the vertical temperature. The current and the power consumption are recorded At the each point of the measurement.

Note:
Clime rate of temperature should varies depends on the room temperature, installation of the heater and other circumstances.
However, it came out that when you put the heater in open air in the normal room temperature the rise of the cartridge temp is proportional to voltage & current.

## We broke a tester

There is something you need to pay a tension when measuring current with a tester.

This will form short circuit that goes through a tester, consequently melts down the inner fuse.

Correct way of measuring current should look like this.