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Field Problems of Electrical Meters
Single Phase Meters
- PROBLEM: Meter disk rotating backwards under load.
REASON: Line and load wires are reversed. There is no meter defect that will cause a meter to run backwards.
- PROBLEM: Meter reading less than previous reading.
REASON: Wrong reading last time meter was read. The wrong reading was higher than this month’s which presumably was read correctly.
Note: This usually occurs with pointer type meters, and when a pointer is on or near 9.
- PROBLEM: Meter disk does not stop immediately when load is disconnected.
REASON: Creeping meter
- PROBLEM: Meter disk moves constantly. Could be backward or forward.
REASON: Nothings wrong. Disk is drifting to electrically balanced position when load is disconnected.
EXCEPTION: If disk makes a complete revolution without stopping, it is “creeping”. This is a defect. (Watch the black mark on the edge of the disk. If it makes a complete revolution, It is creeping.
- PROBLEM: Load passes through meter, but disk does not move.
REASON #1: Voltage not reaching meter.
REASON #2: Potential clip connection not tight, or not closed. (Same as #1, no voltage.)
REASON #3: Meter is defective. Probably mechanical difficulty.
REASON #4: The load is too small to overcome the starting friction. A slightly higher load is the fix.
- PROBLEM: Meter disk spins fast before then slows down.
REASON: Electric motors have a rush of current when first turned on. This is normal.
Form 2S, 240 Volt, 3 Wire Meters Connected for Use in 120 Volt 2 Wire Circuits.
- PROBLEM: Newly installed 240 volt, 3 wire meter wired for 120 volt, neutrally connected to the back of the meter, but it doesn’t register.
REASON #1: Line and load wires are reversed. There is no meter defect that will cause a meter to run backwards.
REASON #2: If disk turns, register gear not meshing with disk shaft.
- PROBLEM: Newly installed meter trips the breaker when energized.
REASON #1: Neutral wire to the potential connection on back of meter is on the wrong screw or the potential clip may not have been opened.
REASON #2: Other wiring problem not meter related.
- PROBLEM: Meter not registering all of load. Running too slow.
REASON: Wiring error. Possibly load is passing through just one meter coil. The load must pass through both meter current coils to register 100%. The load passes through coil one side from top to bottom and through the coil on other side from bottom to top.
- PROBLEM: I am installing this meter on a 480 volt circuit and the nameplate reads 240 volt.
REASON :The voltage connected to the meter potential coil is not 480. It is 277 and this 240 volt meter is made. Especially for a 277/480 volt way circuit.
- PROBLEM: I am connecting this meter in a 277 volt circuit, but the meter nameplate reads 240 volts. Isn’t the circuit voltage too high?
REASON :No. It can handle the higher voltage and still be accurate within tolerances.
- PROBLEM: Newly installed meter disk won’t turn.
REASON #1: CT secondaries still short circuited. Check terminals and move terminal cap screw containing short circuiting switch to open position. Or if there is no short circuiting switch, remove jumper between terminals.
REASON #2: No voltage to meter terminals.
REASON #3: No load.
REASON #4: Mechanical defect.
REASON #5: Reversed polarity on one CT causing reversed torque on one stator. With no single phase load, meter disk will stand still (bucking stators).
REASON #6: Consumer’s load wires passing through one CT in reverse direction causing same condition as in Answer 5.
REASON #7: Reversed polarity of voltage connections to 3 wire stator.
- PROBLEM: I`m using this meter on 480 volts. The nameplate reads 240. Can I use this meter?
REASON : No. The meter potential coil is connected to just 277 volts.
- PROBLEM: This meter will be connected to 277 volts, but the meter nameplate reads 240. Will this overload the coils?
REASON :No. The coils can handle that and meter will remain accurate.
- PROBLEM: You sent the wrong meter. I ordered a 3 phase meter. This is a single phase meter. It has only 4 terminals. So does the meter socket that you sent with it.
REASON : The meter actually has 5 terminals. The 5th terminal is in the 9 o’clock position and it is somewhat smaller than the others. You might miss it on a quick look. The meter socket has only 4 terminals, as you say, but included with your order is a field installed 5th terminal.
- PROBLEM: How can this 5 terminal meter measure 3 phases when only 2 phases go through the meter?
REASON : Because it follows the rules of metering which states that correct metering requires one less stator than there are wires in the circuit. The reason is that all the current in the “unmetered” phase will register on the meter while passing through the current coils of the other two “metered” phases.
- PROBLEM: Can I use this 240 volt 3 phase meter on just one phase with a neutral?
REASON : Yes. Connect the phase wire to either of the top terminals and the neutral to the 5th terminal. The load wire must be connected to the bottom terminal directly beneath the top terminal you are using. Abandon the remaining terminals. The meter will operate just as a 2 wire meter would. (After all, this meter is merely 2 -2 wire meters under one glass cover.)
- PROBLEM: I am using this meter on 480 volts, but the meter nameplate says this is a 240 volt meter. Do I have the wrong meter? I ordered a 480 volt meter.
REASON : See Form 6S, complaint # 2.
- PROBLEM: I am connecting 277 volts to this meter but the nameplate reads only 240 volts.
REASON : See Form 6S, complaint #3