Testing a Model T Generator Armature Using a Growler
Dec 29, · In this video I check out an armature from a DC generator using a growler. The two fixed probes are placed touching two adjacent commutator segments (one winding) with the growler turned on and the armature mounted in the electromagnetic cradle. There is an Ammeter wired in series with the probe tips. The magnetic field produced by the growler will create a current in the armature winding under test.
The Magneto Guys. Using the Growler A growler is a useful piece of equipment used for testing armatures. It consists armwture a U shaped iron core which has a coil wound around the arms. Often, this coil is in two sections which can be switched to a series or parallel connection as required.
The two ends of the U shaped core are angled in such a way that a wound armature can sit in the gap thereby completing a magnetic circuit. This arrangement allows the armature to be tested for both shorted and open windings. Testing for shorted windings Any armature coil which has a short will create a closed circuit and an alternating current will be induced in the shorted turn s.
It will also create an alternating magnetic field around the shorted armature coil. A flat, metal feeler containing iron, such as a hacksaw blade, can be used to detect the magnetic field generated by a shorted armature coil. The feeler is held lightly in line with each armature slot in turn.
Normally, no pull will be felt on the feeler but when it is over a slot containing a shorted coil, the alternating magnetic field will alternately attract and release the feeler. This will cause it to vibrate in sync with the alternating current and this vibration, together with the growling noise, indicates that a shorted coil has been found. Not all armatures can be tested ue short circuits in this way.
Some armatures produce excessive vibration of the feeler all around the armature during the test. The two test probes are placed on adjacent commutator segments and the meter reading noted. Then, keeping the probes stationary, the armature is rotated in the jaws bringing each pair of segments texter the test probes in turn.
The readings should be nearly the same for each pair of adjacent segments. If a coil is short-circuited, the ammeter reading will drop to almost zero. Testing for what did japan attack pearl harbor windings One method of testing for open windings is to use the probes and ammeter exactly as described above.
A zero reading on the ammeter indicates a broken winding or open coil. A rather more crude but none armatkre less, effective test for open windings involves placing the armature on the growler and using the feeler to short circuit the ends of the coils.
This can be done by successively shorting adjacent commutator segments. Note that good coils will create sparks - no spark indicates that the coil is open circuit. In order that the smooth brush surfaces are not testfr by the sparking, it is important to place the feeler on the riser part of adjacent commutator segments, armwture on the brush surfaces themselves.
When the test requires the armature to be rotated in the jaws of the growler it is not always easy to do so because the growler acts as an electromagnet and grips the armature quite tightly, particularly with larger armatures.
For this reason, a foot switch is often used for turning the growler current on and off as the armature is being rotated. Use of a foot switch also leaves both hands free to hold the probes. Testing for grounded windings Most of the older growlers have a built in continuity test circuit consisting of a pair of probes and a bulb. Small faces whatcha gonna do about it lyrics one probe on the armature shaft and the other on each commutator segment in turn, lights the bulb if a short to us exists.
The picture shows where the probes would be placed but we choose not to use this method so did not wire up the probes when we rewired the growler. Note that, if this test is used, the growler is not switched on but is simply used as a convenient way to hold the armature while the test is carried out. The continuity test setting on digital multimeters could be used instead. In our view, this testrr is best done with a standard insulation test meter.
All the above notes refer to the use of the growler to test dynamo armatures. We also use a growler as how to dehydrate eggs for powdered eggs of the testing procedure for all of our rewound magneto armatures.
The growler acts as a transformer as before but here we have two secondary windings how to meet gary in club penguin the primary and secondary windings of the magneto armature.
The design of the magnetic circuit and the number of coil turns in the growler itself will also have an effect so different growlers will give different figures for the same magneto armature. We always use the same growler for these tests so some factors are kept constant.
As an example, many previous what does remedial massage mean have shown that, for a Lucas K2F armature tested on our growler, we should expect a primary voltage of v and a secondary voltage of volts — which explains the use of the HV probe shown in the picture.
Much variation on these figures would indicate a possible problem that needs investigating further. Email: workshop themagnetoguys.
May 10, · Instagram | chesapeakecharge.com is a how to test a armature for starters or generators using a Growler. This Silver Beauty, model Feb 02, · The growler is switched on and a thin piece of ferrous metal – usually an old hacksaw blade, is run along the core of the armature. If a short exists, the hacksaw blade . The two test probes are placed on adjacent commutator segments and the meter reading noted. Keeping the armature stationary in the growler’s jaws, the two probes are ‘walked’ around the commutator segments until the highest reading is obtained. If required, this reading can be adjusted on the meter by use of the growler’s variable resister.
Any generator or motor repair shop will have one of these tools. All three capabilities are desirable to comprehensively test an armature. A Growler may have a set of two probes with a low wattage light bulb in series to make continuity test for low resistance shorts. A Growler may have a single probe with two tips at a fixed distance apart. It can be placed on two adjoining commutator segments with the growler operating.
This can be used to measure the current in a particular winding. An Ammeter will indicate the amount of current in the winding. We all know that by moving a loop of wire through a magnetic field a current is produced in the wire.
The growler has a transformer with a set of open circuit magnetic laminations a cradle where you can place the armature. This magnetic field is impressed upon the armature windings when the armature is present in the cradle. In a good armature there is no closed circuit loop in any of the windings i. Hence there is no current in the windings and no magnetic field from the windings is produced. In this condition when the hacksaw blade is placed parallel to the top of the laminations while rotating, the armature the blade will not vibrate.
The armature must be rotated in the transformer cradle without moving the hacksaw blade to check each armature winding. If there is as an intra or inter winding short in the armature windings, an alternating magnetic field will be created in the laminations associated with the closed-circuit loop winding causing the hacksaw blade to vibrate rapidly and noisily.
If the growler is equipped with this test capability there will be a set of two probes that are used to make continuity tests. See Figure 1 and 3. These probes have a low wattage test lamp wired in series which will light when the tips of the probes are connected to each other. By placing the Black probe on the armature shaft ground and the Red probe on any of the commutator segments remember they are all connected together in series if there is a winding short to ground the lamp will light indicating a short is present.
If the lamp does not light there are no windings shorted to ground. Caution: The two probes are connected directly to Volt AC power at all times when the growler is plugged into a wall outlet. This test — in Figure 4 below — measures the relative current flowing in each individual armature winding. The amount of current flowing in each of the windings should be approximately the same. It is important to measure the current in each winding with the probes connected AND the armature in the same position on the electromagnetic cradle.
The electromagnet will create different Ammeter readings because the magnetic strength differs based on position of the armature windings to the electromagnetic cradle. The two fixed probes are placed touching two adjacent commutator segments one winding with the growler turned on and the armature mounted in the electromagnetic cradle. There is an Ammeter wired in series with the probe tips. The magnetic field produced by the growler will create a current in the armature winding under test.
The amount of current flowing in each the winding will be shown on the Ammeter scale. The Growler is a specialized tool that all generator and motor repair shops will have. The tests described above take very little time and most repair shops will complete them for a small charge. There is one armature fault the Growler tests above will not detect.
This situation is not very common fault, but does occur. See Figure 2. Figure 2. Growler Testing an Armature If there is as an intra or inter winding short in the armature windings, an alternating magnetic field will be created in the laminations associated with the closed-circuit loop winding causing the hacksaw blade to vibrate rapidly and noisily.
Winding Ground Short Test If the growler is equipped with this test capability there will be a set of two probes that are used to make continuity tests. Figure 4 Winding Current Test The Growler is a specialized tool that all generator and motor repair shops will have.
Copyright Ron Patterson