Major tech MT790, Instruction Manual

To measure AC c AC voltage, connect the Meter as follows: 
1. Dial the Rotary to AAC to select AC C AC Voltage range. 
2. Press the lever to open the transformer jaw. 
3. Center the conductor within the transformer jaw, then release the 

Meter slowly until the transformer jaw is completely closed, Make sure 
the conductor to be tested is placed at the center of the transformer 
jaw, otherwise it will cause deviation. The Meter can only measure one 
conductor at a time, to measure more than one conductor at a time will 
cause deviation. 

4. The double display shows the AC current True RMS value and AC 

voltage True RMS value. 

5. Press 

MAXMIN

, the LCD displays         , it starts recording the 

maximum AC current True RMS value. 

6. Press 

MAXMIN

, the LCD displays        , it starts recording the 

minimum AC current True RMS value. Press

 MAXMIN

, again to show 

the present AC current True RMS value. 

7. The display shows 0L when the current of the tested conductor is 

higher than 1000A rms. 

Note: 

When the measurement has been completed, disconnect the 

connection between the conductor under test and the jaw, and remove 
the conductor away from the transformer jaw of the Meter. 

13

8.4. Active Power (main display) + Phase Angle (secondary 

display) Measurement 

WARNING:

 To avoid damages to the Meter or harms to you, do not 

measure higher than AC voltage 750 v and AC current 1000A. 

To measure active power + phase angle, connect the Meter as follows: 
1. Dial the Rotary to KW to select Active power + Phase angle range. 
2. Press the lever to open the transformer jaw, and clamp them to the 

corresponding phase of tested conductor. If user needs to mesaure any 
phase of the 3 phase, then clamp them to that phase's conductor. 

3. Connecting method (see figure 6, 7, 8): 
4. Insert red, blue, yellow test leads to 

L1, L2, L3

 input terminal and 

connecting it to every live wire of the 3 phase. 

5. Insert black test leads to 

COM 

input terminal and connect it to the 

neutral wire of the 3 phase. 

•   When measuring 3 phase 4 wires, connecting the Meter as figure 6. 

MAX

MIN