Extech 480400 Phase Sequence Tester, 600 V AC, Graphical LCD

Extech 480400 phase sequence tester with graphical LCD

The Extech 480400 is a pocket-size phase sequence tester that shows on a multi-line graphical LCD whether a three-phase supply rotates clockwise or counter-clockwise, and which of the three phases are live. It is rated for 40 to 600 V AC over a 15 to 400 Hz frequency range, which covers 50 Hz and 60 Hz mains as well as higher-frequency ground-power and generator supplies.

The 480400 needs no battery, because it takes its power from the circuit under test. It is built in a double-molded housing, weighs only 130 g, and ships with a cable, three large color-coded alligator clips and a soft case.

Technical specifications of the 480400

The figures above are from the 480400 datasheet and user manual.

How to read the 480400 display

After the clips are connected to the three phases, the L1, L2 and L3 icons appear on the LCD one at a time as each phase is detected, and the rotation arrow with the R or L icon shows the phase sequence of the mains as connected. The manual warns that the rotation arrows can light even when one probe is connected to neutral or earth instead of a phase, so confirm that the clips are on the three phases and not on a neutral.

Because the display is graphical, the reading is easy to take in poor light, and the LCD does not rely on a battery that might be flat at the moment of need. The instrument is intended for supply-side checks; for motor rotation checks without power, a tester that senses the motor, such as the 480403, is the correct tool.

Where the 480400 saves time

• Checking the incoming feeder before connecting a three-phase pump or fan motor.
• Verifying that a generator, ATS or temporary power set has the same sequence as the utility supply.
• Confirming phase rotation at a distribution board after maintenance or after a change in cable terminations.
• Spot checks in panel-building workshops before delivery.

The Extech PRT200 is the choice when conductors are insulated and you do not want to open terminals, and the 480403 when you also need to check motor rotation.

Selection checklist for the 480400

• Confirm that your supply is between 40 and 600 V AC at 15 to 400 Hz.
• Confirm that a battery-free instrument with a graphical LCD suits your team.
• Decide whether you need a non-contact tester (PRT200) or motor rotation (480403) instead.
• Check that the alligator clip jaws are wide enough for the busbars and terminals you work on.

Safe use and maintenance of the 480400

Inspect the leads and clips for damaged insulation before each use and replace damaged items. Treat voltages above 30 V AC rms as a shock hazard, keep fingers behind the finger guards, and verify the tester on a known live source before relying on it. The instrument should not be used in wet conditions or near explosive gas, vapor or dust. Wipe it clean with a damp cloth and store it in the soft case. If the 480400 is used for safety-critical sequence decisions, check it periodically on a source of known sequence.

Applications of the 480400 in Oman and the GCC

Contractors and plant electricians use a battery-free sequence tester whenever new equipment is installed on an LV feeder, because a wrong sequence on a pump leads to reverse rotation and damage to impellers and seals. Maintenance teams at gas plants, water treatment sites and desalination plants check sequence after switchgear work, and workshops that build control panels check each panel before dispatch. The small size makes it easy to keep one in every technician’s kit.

Phase sequence basics for 480400 users

A three-phase supply has three voltages displaced by 120 electrical degrees, and the order in which they reach their peaks is the phase sequence. Swapping any two conductors reverses the sequence. Induction motors run in the opposite direction when the sequence is reversed, while pumps, compressors and screw machines can be damaged by reverse running, and some protective relays and soft starters trip on the wrong sequence.

Record the sequence at the source panel and again at the load terminal box after installation. If the two readings differ, a conductor has been swapped somewhere between them, and the fix is to exchange two phases at one end only, after isolating and locking out the circuit. Label the cable ends once the sequence is confirmed so that later work does not upset it.

Information to send with an RFQ for the 480400

• Part number 480400 and the required quantity
• Supply voltage and frequency
• Quantity and whether a motor rotation tester (480403) is also needed
• Delivery location in Oman or the GCC and the required lead time
• Whether calibration documentation or a traceable calibration certificate is required

Documents and quotation

A datasheet for the Extech 480400 is attached on this page. It lists the voltage range, frequency range and features.

Send us the part number 480400, the quantity and the delivery location in Oman or the GCC, and we will reply with availability and a quotation. Seven Star LLC is an independent supplier in Muscat and is not affiliated with the manufacturer.