Rockwell Automation 1405-M620 User Manual

Installation Instructions

Bulletin 1405 (M620) Operating Instructions

Overview

The MiniPowermonitor (1405-M620) measures all the important parameters of 3-phase power lines in low-voltage AC power applications. The measurements are indicated on a 3-line display, one parameter at time, either by auto-sequencing or by manual access. There are 6 parameter groups:

• Line-to-line voltages

• Line-to-neutral voltages

• Instantaneous, time-averaged and peak currents

• Real power per phase, apparent power per phase, total real and

apparent power, and 3-phase power factor

• Power factor (Cos φ) per phase

• Net real energy: per phase and total for all 3 phases

Phase voltages are monitored continuously for under- and over-voltage conditions, and when such a condition is detected, an alarm relay is activated. Energy units are also transmitted as relay pulses. Relay contacts are connected via rear panel terminal points.

Measured values for each of the 3 phases are indicated simultaneously on bright red 7-segment LED displays, 14 mm high, arranged in 3 horizontal lines of 5 digits each. The displayed values can be easily read even in high ambient light conditions, at substantial viewing distances, and at acute viewing angles.

The left-most 7-segment digit on each of the three lines functions as a limited alphanumeric indicator. These digits, along with the LED status lamps on the right of the instrument front panel, indicate either which measurement parameter is being displayed at any instant, or the set-up status.

The instrument is operated through three key-switches (‘-’, ‘F’, and ‘+’) arranged in a row at the bottom right of the front panel. These keys are used for instrument set-up, and for manual selection of displayed measurements. Different functions are selectable using the function (‘F’) key-switch, by keeping it pressed for varying lengths of time. The left-most character of the lowest display line indicates the selected function.

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External connections to the instrument are terminated on plug-in connector blocks with spring-clamp wire terminals, at the rear of the instrument. Phase voltage connections are terminated on a 7-pin connector block. Another 12-pin connector block is used for the current transformer inputs, and alarm and energy pulse relay outputs.

The instrument’s operating power supply is drawn from a separate 120V or 240V ac power supply input, through an additional 3-pin connector block. An optional 400V or 480V version of the unit is available with operating power drawn from two of the phase voltage input lines (L1 - L2). Therefore the M620 can be used with either 3-wire (3 phase) or 4-wire (3 phase and neutral) power systems.

The M620 is a compact instrument, with a 96 x 96 mm front panel, and a depth of approximately 85 mm.

Installation

Only qualified personnel should install and wire this equipment. Refer to the following safety guidelines prior to installation.

ATTENTION

Only qualified personnel, following accepted safety procedures, should install and wire the MiniPowermonitor. Before beginning any work, disconnect all sources of power and verify that they are de-energized and locked out. Failure to follow these instructions may result in personal injury or death, property damage or economic loss.

ATTENTION

Never open a current transformer (CT) secondary circuit with primary current applied. Wiring between the CTs and the MiniPowermonitor should include a shorting terminal block in the CT secondary circuit. Shorting the secondary with primary current present allows other connections to be removed if needed. An open CT secondary with primary current applied produces a hazardous voltage, which can lead to personal injury, death, property damage or economic loss.

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Bulletin 1405 (M620) Operating Instructions 3

1. Install your module within a suitable enclosure. Make sure the enclosure provides adequate clearance for ventilation and wiring of the module.

Refer to Dimensions on page 20 for dimensions and spacing guidelines for the MiniPowermonitor.

2. Determine your wiring mode and install wiring between the MiniPowermonitor and your power system.

Refer to Electrical Connections on page 3 for more information.

3. Configure the instrument settings to match those used in your power system connections.

Refer to Instrument Set-Up on page 14 for more information.

Grounding

Electrical Connections

MiniPowermonitors do not need to be grounded because of the isolated enclosures. Follow all local requirements for grounding of PT and CT secondaries.

Electrical connections are terminated on two plug-in connector blocks with spring-clamp wire terminals, at the rear of the instrument. These connector blocks, 7- and 12-pin respectively, can accept wire sizes from 28 to 14 AWG (0.08 to 2.5 sq.mm).

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Current Inputs

M620

GND

Aux. Supply

(120V or 240V only)

NCNCL3

NNGND

TIP

Voltage Inputs

Pins 2 and 4 (counting from the left side) of the 7-pin connector are not used: no external wires should be connected to these terminals!

CT Connection: Careful consideration should be given when connecting the secondary of the CT to the current inputs of the MiniPowermonitor. Extended lengths of connection wire will cause the VA rating of the CT to increase and will create higher common mode input voltage. It is recommended that the wire size be selected to limit the impedance to 200 milliohms. Exceeding this limit may cause current readings to become less accurate when using a star connection.

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Aux Supply: With this option, instrument power is supplied by a separate 120V or 240V line, independent of the measured power lines. A third connector block (3-pin, spring-clamp terminals type) is added at the rear with this option.

Bulletin 1405 (M620) Operating Instructions 5

IMPORTANT

Units are rated 120V or 240V but not both. A 120V unit will not accept 240V, and a 240V unit will not accept 120V.

A unit with the 120V supply option is not designed to operate on 240V or any other voltage. Likewise, a unit with the 240V supply option is not designed to operate on 120V or any other voltage. Units designed for 400V and 480V operation do not have an auxiliary supply connection and receive power from the measurement line. Ensure that each unit is properly supplied with a power source that matches the voltage designation of your unit.

Relay Output Connections

Alarm and energy pulse relay contact connections are made to the spring-clamp wire terminals on the 12-pin connector block, as follows:

Table 1 Alarm and Energy Pulse Relay Contact Connections

Measurement Operations

Alarm: Terminals 7 - 8

Energy pulses: Terminals 9 - 10

Immediately after the instrument is switched on, the software version is first displayed for 8 seconds, after which the measured values are displayed. The measured parameter that is displayed when the instrument is switched on will be the main displayed parameter group that was on display when the instrument was switched off. This will happen regardless of whether the instrument was in the “constant parameter” or auto-sequencing display mode at that time the instrument was switched off.

In the “constant parameter” display mode, any one of the 6 parameter groups can be manually selected, by forward or backward sequential stepping, using the “+” or “-“keys. Only that parameter will be displayed, until another parameter is manually selected, or the instrument is switched to auto-sequencing display mode. Some of the parameter groups (current, power, and energy) have a main displayed parameter and also additional parameters within the same group. The additional parameters can be accessed when the instrument is displaying the main parameter of that group. For example, when the instrument is displaying current measurements, the main parameter

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displayed is instantaneous phase currents, while the additional parameters are time-averaged phase currents and peak phase currents. For power measurements, the main parameters displayed are real power for each phase. The additional parameters in this group are apparent power of each phase, total real and apparent power, and 3-phase power factor. When the instrument is displaying the main parameter of a group, the additional parameters within that group can be scrolled using the “F” key.

Measurement Modes

The functions of the instrument are accessed as follows:

Table 2

Key Function

Indication

“+” Skip to the next measured parameter Short

Auto-sequencing display mode: enable / disable

Re-set average and peak values - “c” Very long

“F” Sequentially display one parameter type: e.g.,

current

Enter set-up mode Very long

“-“ Go back to the previous displayed parameter

- “r” Long

Key Press Duration

Short

The instrument measures voltage and current for each of three phases in an alternating sequence of 2 seconds each. This corresponds to the integrating time of the A/D converter circuits. At the same time, the values of power, power factor (Cos f), and energy consumption are computed. The energy value is computed for each phase over the integration period, and the accumulated values are stored in memory.

The measured voltage values are continuously evaluated for over- and under-voltage occurrences, and the energy transfer rate is converted to an output pulse rate. Voltage limit alarms and energy unit pulses are transmitted by relay contacts.

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In the auto-sequencing displayed mode, the displayed parameter change every 6 seconds. The user can halt the auto-sequencing of displayed parameters, so that one desired parameter is displayed continuously. Independent of the sequencing mode, the measured values are updated and displayed in 2-second intervals.

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The measured values of the electrical parameters are available with six analog retransmission outputs (4-20 mA) (optional). Details of these analog outputs are found on

Line-to-line voltage

L1-L2

L2-L3

cos

L1-L3

page 22.

"+" Key Scrolls Down

"-" Key Scrolls Up

Line-to-neutral voltage

V A

L1-N

L2-N

cos

L1-N

V A P

cos

V A P

cos

V A P

cos

V A P

cos

Left:

Instantaneous current

Middle:

cos

Time-averaged current

V A P

cos

Right:

Peak current

Left: Real power Middle: Apparent power Right: Total real power

Total apparent power

Power factor (Cos φ)

cos

3-phase power factor

V A P

cos

V A P

cos

"F" Key Scrolls Right

Left Net real energy L1 L2 L3 Right:

Total net real energy

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Auto-Sequencing Display Mode

In this display mode, the instrument automatically switches the displayed values from one parameter group to the next, at intervals of 6 seconds, cycling continuously through all 6 parameter groups.

Any of the additional parameters can be selected instead of the main parameter. Thereafter only the selected additional parameter will be displayed when the turn of that parameter group comes up during display sequencing. For example, if time-averaged phase currents are selected in the current (I) parameter group, only these values will be displayed when it is the turn of this group during auto-sequencing. Irrespective of the specific parameter selected for display within each group, the total period of the display cycle for the 6 parameter groups remains constant.

Line-to-neutral voltages and line-to-line voltages are treated as separate parameter groups, so that both these parameters are always displayed during auto-sequencing.

Analog Outputs

Examples of all the parameter displays, and parameters grouping, are illustrated on the next page.

The M620 is also available with six analog retransmission outputs. These outputs can be user programmed for 0-20 mA or 4-20 mA, and assigned to any of the measured power-line measured variables. These outputs are electrically isolated from the rest of the instrument’s circuits. Each output has a positive polarity. A common return line at 0 V potential is used for all analog outputs. Each output can drive a load of up to 250 ohms, with output voltage of up to 5V dc. These outputs may be connected in parallel.

Configure the analog outputs during instrument setup. The following key sequences and indications apply during setup.

The “-” key scrolls through the parameters that may be assigned as a

0 to 20 mA output:

VVoltage P-P nVoltage P-N I Current instantaneous = Current time average Preal power S apparent power

C cos phi (power factor)

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