Dynamometer

The watt thou is an electrodynamic instrument for standard the electric power or the cater rate of electric energy of any given locomote. The device consists of a pair of fixed spins, known as authoritative loops, and a assignable whirl known as the potential roll. The received coils are attached in series with the circuit, while the potential coil is connected in parallel. Also, on analog wattmeters, the potential coil carries a needle that moves everyplace a scale to indicate the flyerment.A current f get-going through with(predicate) the current coil generates an electrocharismatic national around the coil. The strength of this field is proportional to the line current and in phase with it. The potential coil has, as a general rule, a high-value resistance connected in series with it to reduce the current that flows through it. The result of this arrangement is that on a dc circuit, the deflection of the needle is proportional to both the current and the voltage, thus conforming to the equation W=VA or P=EI.On an ac circuit the deflection is proportional to the average instantaneous harvest-time of voltage and current, thus measuring rod true power, and possibly (depending on vitiate characteristics) demonstrate a different rendition to that obtained by simply multiplying the readings showing on a stand-alone voltmeter and a stand-alone ammeter in the equal circuit. The two circuits of a wattmeter are likely to be damaged by excessive current.The ammeter and voltmeter are both vulnerable to overheating in issue of an overload, their arrows will be driven off scale but in the wattmeter, either or even both the current and potential circuits squeeze out overheat without the pointer approaching the end of the scale This is because the position of the pointer depends on the power factor, voltage and current. Thus, a circuit with a low power factor will give a low reading on the wattmeter, even when both of its circuits are loaded to the maximum base hit limit.Therefore, a wattmeter is rated not only in watts, but also in volts and amperes. Retrieved from http//en. wikipedia. org/wiki/Wattmeter (A ergometer consists of an absorption (or absorber/driver) unit, and usually includes a means for measuring tortuosity and rotational locomote. An absorption unit consists of virtually type of rotor coil in a housing. The rotor is coupled to the engine or other equipment nether test and is free to rotate at whatever speed is compulsory for the test.some(a) means is provided to develop a braking torsion between dynamometers rotor and housing. The means for developing contortion cannister be frictional, hydraulic, electromagnetic and so forth according to the type of absorption/driver unit. One means for measuring torque is to mount the dynamometer housing so that is free to give up except that it is restrained by a torque arm. The housing can be made free to rotate by using trunnions connected to each end of the h ousing to support the dyno in pedestal mount trunnion bearings.The torque arm is connected to the dyno housing and a weighing scales is positioned so that it measures the force exerted by the dyno housing in attempting to rotate. The torque is the force indicated by the scales multiplied by the length of the torque arm measured from the cracker bonbon of the dynamometer. A load cell transducer can be substituted for the scales in parade to provide an electrical signal that is proportional to torque. Another means for measuring torque is to connect the engine to the dynamometer through a torque sensing coupling or torque transducer.A torque transducer provides an electrical signal that is proportional to torque. With electrical absorption units, it is possible to determine torque by measuring the current drawn (or generated) by the absorber/driver. This is more often than not a less accurate method, but it may be adequate for some purposes. A wide variety of tachometers are availa ble for measuring speed. Some types can provide an electrical signal that is proportional to speed. When torque and speed signals are available, test data can be transmitted to a data acquisition system rather than being recorded manually. recreate and torque signals can also be recorded by a chart recorder or plotter. ) Power in an electric circuit is the product (multiplication) of voltage and current, so any meter designed to measure power must account for both of these variables. A special meter movement designed especially for power measurement is called the dynamometer movement, and is alike(p) to a DArsonval or Weston movement in that a whippersnapper coil of fit is attached to the pointer mechanism.However, unlike the DArsonval or Weston movement, another (stationary) coil is used instead of a permanent magnet to provide the magnetic field for the moving coil to react against. The moving coil is broadly energized by the voltage in the circuit, while the stationary coil is generally energized by the current in the circuit. A dynamometer movement connected in a circuit looks something like this pic The top (horizontal) coil of wire measures load current while the bottom (vertical) coil measures load voltage. honourable like the lightweight moving coils of voltmeter movements, the (moving) voltage coil of a dynamometer is typically connected in series with a range resistor so that full load voltage is not applied to it. Likewise, the (stationary) current coil of a dynamometer may have precision ringway resistors to divide the load current around it. With custom-built dynamometer movements, shunt resistors are less likely to be require because the stationary coil can be constructed with as heavy of wire as needed without impacting meter response, unlike the moving coil which must be constructed of lightweight wire for minimum inertia.