Figure 3
and work your way down .
RMS multimeter ; ‘ A U T O ’ should appear in the window when turned on . When manually ranging start at the highest amps scale
TURN ON THE POWER AND TAKE YOUR READING .
Turn the power off and disconnect the multimeter from the circuit . Reconnect the tested circuit . The clamp meter shown in Figure 2 is used to measure amperages from . 01 to 200 mAdc using its test leads and can measure amperages from . 01 to 500Aac using its clamp around feature . DC Amperage The testing of DC amperage around heating equipment is normally done in the microamp (µ A ) range . DC microamp testing is normally done on gas systems or on powerburners that incorporate flame safeguard systems using flame
Figure 4 r o d s o r ultraviolet or infrared detectors .
When testing DC microamps an adapter , like our FSG1 , Figure 4 , which will allow the multimeter to take these measurements must be used . The adapter goes from a small jack ( RCA ) on the control to the leads of the meter and polarity is not required
The leads must be in the COM and mA terminals of the 81B and the meter set to record DC amperage . If the readings are read as a
Figure 5 negative ( -) by the meter the leads are reversed .
In Figure 5 we show a typical commercial powerburner control that requires this adapter and in Figure 6 we show the Figure 6 adapter connected to a gas control that is used on residential and commercial burners . The readings taken using the
Figure 7 meter should be within the guidelines called out by each manufacturer in their literature .
AC AMPERAGE
Figure 8
As previously stated , there are three meters that may be used by heating technicians to determine the AC Amperage that may be present in circuits that make up the heating systems that we install and service .
The first is the low-range ammeter . It is used to set the differential on adjustable heat anticipator type thermostats .
The second type of meter is the clamparound V-O-A , volt-ohm-ammeter , Figure 2 . It allows you to read voltages and resistances and is similar in operation and function to a multimeter when used to check resistances and voltages . Its single most important feature is its ability to read amperages without having to power down and disconnect the circuit . By opening the ‘ jaw ’ of the device and placing it around a wire in the circuit
Figure 9
the amperage flow through the circuit can be observed . This type of meter is especially helpful in reading motor startup and running amperages . To use the instrument , simply place it around one of
Figure 10 the power leads entering or leaving a circuit or load . It does not matter which wire is used since we are monitoring the total draw of the circuit . In Figure 7 we show a V-O-A being used to observe the amperage draw of a PSC powerburner motor .
The third type of meter that can be used to measure amperages in heating circuits is the multimeter , Figure 1 . When placed into the circuit , as previously described , it can measure the amperage flow across any device found around heating equipment . Figure 11
AMPERAGE TROUBLESHOOTING - DC AMPERAGE
To test amperages using the 81B , Figure 1 , for reference :
Select the correct DC Amps Scale by rotating the center rotary scale . Keep in mind that the 81B has three amperage scales ; amps ( A ), milliamps ( mA ) and microamps (µ A ).
Make sure that the meter leads are in the
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