MicroLogic™ 5.0P and 6.0P Electronic Trip Units – Instruction Bulletin PDF
48049-137-06EN

General Information

Introduction

MicroLogic™ trip units provide adjustable tripping functions on electronic trip circuit breakers. The product name (A) specifies the level of protection provided by the trip unit.

MicroLogic trip units are field replaceable to allow for upgrading of the trip unit in the field. For complete information on available circuit breaker models, frame sizes, interrupting ratings, sensor plugs, rating plugs and trip units, see the product catalog.

MicroLogic Trip Unit

      
  A Product Name
  B Trip Indicators
  C Battery Housing
  D Adjustable Switches
  E Switch Cover
  F Sealing Tab
  G Adjustable Rating Plug
  H Reset Button for Battery Status Check and Trip Indicators
  I External Terminal Block Connection
     
     

Communications

WARNING
Potential compromise of system availability, integrity, and confidentiality
  • Change default passwords at first use to help prevent unauthorized access to device settings, controls and information.
  • Disable unused ports/services and default accounts to help minimize pathways for malicious attackers.
  • Place networked devices behind multiple layers of cyber defenses (such as firewalls, network segmentation, and network intrusion detection and protection.
  • Use cybersecurity best practices (for example, least privilege, separation of duties) to help prevent unauthorized exposure, loss, modification of data and logs, or interruption of services.
Failure to follow these instructions can result in death, serious injury, or equipment damage.

MicroLogic trip units can communicate with other devices via “Modbus” through the Circuit Breaker Communication Module (BCM). For information on the communication feature, see the product catalog and Modbus Communications System Product Data Bulletin 0613DB0702.

Power and Control Settings

Using the graphic display screen and keypad on the trip unit, trip unit options can be set or system measurements checked. See Graphic Display Navigation for more information. System measurements can also be checked using the System Manager Software (SMS), Version 3.2 or later, or other network system management software.

Switch Settings

On the face of the trip unit are adjustable switches to allow changing of the LSI or LSIG trip characteristics of the trip unit. Trip units are shipped with the long-time pickup switch set at 1.0 and all other trip unit switches set at their lowest settings. All advanced protection settings are turned “off.”

Fine switch adjustments can be made with the navigation keys. See Switch Settings Adjustment.

MicroLogic 5.0P Trip Unit

5.0P Trip Unit

      
  A Graphic display screen
  B

Protection menu button (Button includes an LED indicating the active menu)
  C

Maintenance menu button (Button includes an LED indicating the active menu)
  D

Metering menu button
  E

Down button
  F

Up button
  G

Enter button
  H

Long-time pickup (Ir) switch
  I

Long-time delay (tr) switch
  J

Short-time pickup (Isd) switch
  K

Short-time delay (tsd) switch
  L

Instantaneous pickup (Ii) switch
  M

Test plug receptacle
  N

Long-time pickup overload indicator light
  O

Reset button for battery status check and trip indicator LED
  P

Self-protection and advanced-protection indicator light
  Q

Short-time or instantaneous trip indicator light
  R

Long-time trip indicator light
     

MicroLogic 6.0P Trip Unit

6.0P Trip Unit

      
  A Graphic display screen
  B

Protection menu button (Button includes an LED indicating the active menu)
  C

Maintenance menu button (Button includes an LED indicating the active menu)
  D

Metering menu button
  E

Down button
  F

Up button
  G

Enter button
  H

Long-time pickup (Ir) switch
  I

Long-time delay (tr) switch
  J

Short-time pickup (Isd) switch
  K

Short-time delay (tsd) switch
  L

Instantaneous pickup (Ii) switch
  M

Ground-fault protection pickup (Ig) switch
  N

Ground-fault protection delay (tg) switch
  O

Test plug receptacle
  P

Ground-fault push-to-trip button
  Q

Long-time pickup overload indicator light
  R

Reset button for battery status check and trip indicator LED
  S

Self-protection and advanced-protection indicator light
  T

Ground-fault trip indicator light
  U

Short-time or instantaneous trip indicator light
  V

Long-time trip indicator light
     

LSIG Protection

Long-Time Protection

Long-Time Protection Switches

MicroLogic 5.0P
Trip Unit

MicroLogic 6.0P
Trip Unit

Long-time protection protects equipment against overloads.

  • Long-time protection is standard on all trip units.

  • Long-time pickup (Ir) (A) sets the maximum current level based on sensor plug rating (In) which the circuit breaker will carry continuously. If current exceeds this value, circuit breaker will trip after the preset time delay. The long-time pickup (Ir) is adjustable from 0.4–1.0 times the circuit breaker sensor plug rating (In) (D).

  • Long-time delay (tr) (B) sets the length of time that the circuit breaker will carry an overcurrent below the short-time or instantaneous pickup current level before tripping. Two options are available:

    • Standard I2t long-time delay curve. See for I2t long-time delay settings.

    • Idmtl (inverse definite minimum time lag) long-time delay curves vary in slope to enhance selectivity.

Option Description Curve
DT Definite time Constant
SIT Standard inverse time I0.5t
VIT Very inverse time It
EIT Extremely inverse time I2t
HVF High-voltage fuse compatible I4t

  • The overload indicator light (C) indicates that the long-time pickup threshold Ir has been exceeded.

NOTE: MicroLogic trip units are powered from the circuit to always provide fault protection. All other functions (display, metering, communications, etc.) require external power. See MicroLogic Setup for more information.

MicroLogic Trip Unit I2t Long-Time Delay Values

Setting* Long-Time Delay in Seconds*
tr at 1.5 x Ir 12.5 25 50 100 200 300 400 500 600
tr at 6 x Ir 0.5 1 2 4 8 12 16 20 24
tr at 7.2 x Ir 0.34* 0.69 1.38 2.7 5.5 8.3 11 13.8 16.6

  • For MasterPacT™ NT and NW circuit breakers, sensor value (In) can be changed by replacing sensor plug (D) located below the trip unit. For further information, see the instructions packed with the sensor plug replacement kit.

  • Neutral protection is not available when Idmtl protection is selected.

  • The Idmtl selections do not utilize the same thermal imaging feature as the I2t long-time protection function. Both the basic long-time protection and Idmtl EIT are I2t curves, but the different thermal imaging features result in different system performances. For welding applications it is recommended the basic I2t long-time protection be used to ensure expected system performance.

  • Both long-time pickup and long-time delay are located on the field-replaceable adjustable rating plug. To change settings to more precisely match the application, various rating plugs are available. For instructions on replacing the rating plug, see Adjustable Rating Plug Replacement.

  • Long-time protection uses true RMS measurement.

Thermal imaging provides continuous temperature rise status of the wiring, both before and after the device trips. This allows the circuit breaker to respond to a series of overload conditions which could cause conductor overheating, but would go undetected if the long-time circuit was cleared every time the load dropped below the pickup setting or after every tripping event.

NOTE: If checking trip times, wait a minimum of 15 minutes after circuit breaker trips before resetting to allow the thermal imaging to reset completely to zero or use a test kit to inhibit the thermal imaging.

MicroLogic Trip Unit Idmtl Long-Time Delay Values

Option Setting* Long-Time Delay in Seconds Tolerance
DT tr at 1.5 x Ir 0.52 1 2 4 8 12 16 20 24 +0/-20%
tr at 6 x Ir 0.52 1 2 4 8 12 16 20 24 +0/-20%
tr at 7.2 x Ir 0.52 1 2 4 8 12 16 16.6 16.6 +0/-20%
tr at 10 x Ir 0.52 1 2 4 8 12 16 16.6 16.6 +0/-20%
SIT tr at 1.5 x Ir 1.9 3.8 7.6 15.2 30.4 45.5 60.7 75.8 91 +0/-30%
tr at 6 x Ir 0.7 1 2 4 8 12 16 20 24 +0/-20%
tr at 7.2 x Ir 0.7 0.88 1.77 3.54 7.08 10.6 14.16 17.7 21.2 +0/-20%
tr at 10 x Ir 0.7* 0.8 1.43 2.86 5.73 8.59 11.46 14.33 17.19 +0/-20%
VIT tr at 1.5 x Ir 1.9 7.2 14.4 28.8 57.7 86.5 115.4 144.2 173.1 +0/-30%
tr at 6 x Ir 0.7 1 2 4 8 12 16 20 24 +0/-20%
tr at 7.2 x Ir 0.7 0.81 1.63 3.26 6.52 9.8 13.1 16.34 19.61 +0/-20%
tr at 10 x Ir 0.7* 0.75 1.14 2.28 4.57 6.86 9.13 11.42 13.70 +0/-20%
EIT tr at 1.5 x Ir 12.5 25 50 100 200 300 400 500 600 +0/-30%
tr at 6 x Ir 0.7* 1 2 4 8 12 16 20 24 +0/-20%
tr at 7.2 x Ir 0.7* 0.69 1.38 2.7 5.5 8.3 11 13.8 16.6 +0/-20%
tr at 10 x Ir 0.7* 0.7* 0.7* 1.41 2.82 4.24 5.45 7.06 8.48 +0/-20%
HVF tr at 1.5 x Ir 164.5 329 658 1316 2632 3950 5265 6581 7900 +0/-30%
tr at 6 x Ir 0.7* 1 2 4 8 12 16 20 24 +0/-20%
tr at 7.2 x Ir 0.7* 0.7* 1.1* 1.42 3.85 5.78 7.71 9.64 11.57 +0/-20%
tr at 10 x Ir 0.7* 0.7* 0.7* 0.7* 1.02 1.53 2.04 2.56 3.07 +0/-20%

Short-Time Protection

Short-Time Protection Switches

MicroLogic 5.0P
Trip Unit

MicroLogic 6.0P
Trip Unit

Short-time protection protects equipment against short circuits.

  • Short-time protection is standard on 5.0P and 6.0P trip units.

  • The short-time pickup (Isd) (A) sets current level (below instantaneous trip level) at which circuit breaker will trip after the preset time delay.

  • The short-time delay (tsd) (B) sets the length of time that the circuit breaker will carry an overcurrent above the short-time pickup current level before tripping.

  • The I2t on/I2t off option provides improved selectivity with downstream protective devices:

    • With I2t off selected, fixed time delay is provided.

    • With I2t on selected, inverse time I2t protection is provided up to 10 x Ir. Above 10 x Ir, fixed time delay is provided.

  • Intermittent currents in the short-time tripping range which do not last sufficiently long to trigger a trip are accumulated and shorten the trip delay appropriately.

  • Short-time protection can be zone-selective interlocked (ZSI) with upstream or downstream circuit breakers. Setting tsd to the 0 setting turns off zone-selective interlocking.

  • Short-time protection uses true RMS measurement.

  • Short-time pickup and delay can be adjusted to provide selectivity with upstream or downstream circuit breakers.

NOTE: Use I2t off with ZSI for proper coordination. Using I2t on with ZSI is not recommended as the delay in the upstream device receiving a restraint signal could result in the trip unit tripping in a time shorter than the published trip curve.

MicroLogic Trip Unit Short-Time Delay Values

Setting Short-Time Delay
I2t off (ms at 10 Ir) (seconds) 0 0.1 0.2 0.3 0.4
I2t on (ms at 10 Ir) (seconds) – 0.1 0.2 0.3 0.4
tsd (min. trip) (milliseconds) 20 80 140 230 350
tsd (max. trip) (milliseconds) 80 140 200 320 500

Instantaneous Protection

Instantaneous Protection Switches

MicroLogic 5.0P
Trip Unit

MicroLogic 6.0P
Trip Unit

Instantaneous protection protects equipment against short circuits with no intentional time delay.

  • Instantaneous protection (Ii) (A) is standard on all trip units.

  • Instantaneous protection is based on the circuit breaker sensor rating (In).

  • Circuit breaker open command is issued as soon as threshold current is exceeded.

  • Instantaneous protection uses peak current measurement.

  • When instantaneous protection switch is set to off, the instantaneous protection is disabled.

MicroLogic Instantaneous Values

Setting Interruption Current
Ii (= In x..) 2 3 4 6 8 10 12 15 off

Ii = instantaneous

In = sensor rating

Pickup accuracy ± 10%

Ground-Fault Protection for Equipment

Ground-Fault Protection Switches

Equipment ground-fault protection protects conductors against overheating and faults from ground-fault currents (≤ 1200 A).

  • Equipment ground-fault protection is standard on 6.0P trip units.

  • Ground-fault pickup (Ig) (A) sets ground current level where circuit breaker will trip after the preset time delay.

  • Ground-fault delay (tg) (B) sets the length of time that the circuit breaker will carry a ground-fault current above the ground-fault pickup current level before tripping.

  • Equipment ground-fault protection can be zone-selective interlocked (ZSI) with upstream or downstream circuit breakers. Setting the ground-fault delay (tg) to the 0 setting turns off zone-selective interlocking.

  • Neutral protection and equipment ground-fault protection are independent and can operate concurrently.

NOTE: Use I2t off with ZSI for proper coordination. Using I2t on with ZSI is not recommended as the delay in the upstream device receiving a restraint signal could result in the trip unit tripping in a time shorter than the published trip curve.

MicroLogic Trip Unit Ground-Fault Pickup Values

Ig (= In x....) A B C D E F G H J
In ≤ 400 A 0.3 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
400 A < In ≤ 1200 A 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
In > 1200 A 500 A 640 A 720 A 800 A 880 A 960 A 1040 A 1120 A 1200 A

In = sensor rating.
Ig = ground-fault pickup.

MicroLogic Trip Unit Ground-Fault Delay Values

Setting Ground-Fault Delay
I2t off (ms at In) (seconds) 0 0.1 0.2 0.3 0.4
I2t on (ms at In) (seconds) – 0.1 0.2 0.3 0.4
tsd (min. trip) (milliseconds) 20 80 140 230 350
tsd (max. trip) (milliseconds) 80 140 200 320 500

MicroLogic Trip Unit Configuration

Control Power

The P trip unit is designed to be used with an external 24 Vdc power supply. The large LCD display used by the P trip unit requires too much current to be powered by current flow through the circuit breaker.

The P trip unit has a circuit voltage power supply which will power the trip unit when there is approximately 150 Vac or more between two phases. The standard configuration for the voltage probes inside the circuit breaker is at the bottom connections. If the circuit breaker is open in a top fed application, there is no voltage at the bottom of the circuit breaker and the trip unit will not be powered.

The following will be powered and functional even if the trip unit is not externally powered:

  • Fault protection for LSIG functions. The P trip unit is fully circuit powered for fault protection.

  • LED trip indication (powered by an onboard battery). The battery’s only function is to provide LED indication if all other power is off.

  • Ground-fault push-to-trip button works for testing ground fault when the trip unit is powered by the circuit voltage power supply. The ground-fault push-to-trip is also functional if a test kit is powering the trip unit.

The following will be powered and functional with external power:

  • All of the above functions which are functional without external power.

  • LCD display and backlight are functional. Backlight intensity is not controlled or adjustable, and may be different from one trip unit to another.

  • All metering, monitoring, and history logs are functional.

  • Communications from the trip unit to M2C and M6C programmable contact modules are powered by a 24 Vdc power supply at F1 and F2. The M6C also required an external 24 Vdc power supply.

  • Modbus communciations are functional, using a separate 24 Vdc power supply for the circuit breaker communications module. This separate 24 Vdc power supply is required to maintain the isolation between the trip unit and communications.

  • The ground-fault push-to-trip is also functional if a test kit is powering the trip unit.

External Power Supply

CAUTION
HAZARD OF Shock, arc flash or Equipment damage
Trip unit and communication module must use separate power supplies.
Failure to follow these instructions can result in injury or equipment damage.

The trip unit can be powered by:

  • 24 Vdc external power supply (recommended).

  • Over 150 V on the bottom circuit breaker terminals on two phases.

  • Over 150 V on the top circuit breaker terminals with external voltage option.

Power Supply Specifications

Function Specification
Power for Trip Unit Alone 24 Vdc, 50 mA
Minimum Input-to-Output Isolation 2400 V
Output (Including Max. 1% Ripple) ±5%
Dielectric Withstand (Input/Output) 3 kV rms
Connections Connections UC3

Power supply is used for:

Graphic screen display when the circuit breaker is open and top fed.

Option of linking an alarm to a relay output.

To maintain date and time when the circuit breaker is open.

MicroLogic Setup

Use the Maintenance Menu by pressing the wrench key.

NOTE: If trip unit is connected to a communication network which provides date and time synchronization, date/time cannot be set from trip unit.

See MicroLogic Trip Unit Setup for step-by-step instructions to set up the MicroLogic trip unit.

See Trip Unit Configuration for other trip unit configurations instructions.

MicroLogic Setup

Advanced Protection

Neutral Protection

Neutral protection protects neutral conductors against overheating.

  • For a three-pole circuit breaker, neutral protection is possible if a neutral current transformer is used.

    • Adjust the neutral using the trip unit keypad.

    • Possible settings are OFF, N/2, N, or 1.6N.

    • Factory setting is OFF.

    • Oversize neutral protection (1.6N) requires use of the appropriate oversize neutral current transformer.

CAUTION
Hazard of equipment damage
If a four-pole circuit breaker neutral pole switch is set to 4P3D setting, the current in the neutral must not exceed the rated current of the circuit breaker. For a three-pole circuit breaker with oversize neutral protection (1.6N), select the appropriate oversize neutral current transformer.
Failure to follow these instructions can result in injury or equipment damage.

  • For a four-pole circuit breaker, set system type using the circuit breaker neutral selector dial .

    • Make fine adjustments using the trip unit keypad, with the circuit breaker dial setting providing the upper limit for adjustment.

    • Factory setting is 4P4D.

  • Neutral protection conductor type has four possible settings:

    • Off—Neutral protection is turned off.

    • N/2—Neutral conductor capacity is one-half that of the line conductors.

    • N—Neutral conductor capacity is the same as that of the line conductors.

    • 1.6N—Neutral conductor capacity is 1.6 times that of the line conductors. (Three-pole circuit breaker only.)

Four-Pole Circuit Breaker Neutral Selector Dial

Neutral Protection Settings for Four-Pole Circuit Breaker

Circuit Breaker Selector Dial Available Keypad Setting
4P 3D Off, N/2, N
3P N/2 N/2
4P 4D N/2,N

MicroLogic Trip Unit Conductor Type

Setting Long-Time Pickup Short-Tme Pickup Instantaneous Ground-Fault Pickup
Trip Unit Neutral Trip Unit Neutral Trip Unit Neutral Trip Unit Neutral
OFF Ir None Isd None Ii None Ig None
N/2 Ir 1/2 Ir Isd 1/2 Isd Ii Ii Ig Ig
N Ir Ir Isd Isd Ii Ii Ig Ig
1.6N Ir 1.6 x Ir Isd 1.6 x Isd* Ii Ii Ig Ig

Alarms

Alarms can be enabled or disabled for protection or load shedding.

  • When an alarm occurs, an entry is made in the alarm log.

  • For a trip unit to activate an alarm, both the pickup level and time delay must be exceeded. Therefore for LSIG protection and advanced protection programmed to trip the circuit breaker, the trip unit will not activate the alarm until the circuit breaker trips. (For example, if a relay is programmed for the long-time pickup Ir, the trip unit will not signal an alarm when the long-time overload indicator lights. The trip unit will only activate the alarm once the long-time overload exceeds the time delay and trips the circuit breaker.)

  • Link alarms to a visual or audible signal by programming the optional M2C or M6C module contacts, when an external 24 V power supply is used on the trip unit.

  • View alarms by:

    • History logs menu

    • The network system management software

  • M2C/M6C contact characteristics:

    • Minimum load of 100 mA/24 V

    • Breaking capacity at a 0.7 power factor

      240 Vac 5 A
      380 Vac 3 A
      24 Vdc 1.8 A
      48 Vdc 1.5 A
      125 Vdc 0.4 A
      250 Vdc 0.15 A

  • When several alarms are activated, screen response/refresh time will be slower.

See Appendix B—Default Settings and Tolerances for default and range values.

Trip Unit Alarms

Alarm Menu Symbol Alarm Trip
Long-time pickup Current protection Ir X X
Short-time pickup Current protection Isd X X
Instantaneous pickup Current protection Ii X X
Ground-fault current Current protection X X
Ground-fault alarm Current protection X X
Current unbalance Current protection Iunbal X X
Phase A maximum demand current Current protection X X
Phase B maximum demand current Current protection X X
Phase C maximum demand current Current protection X X
Neutral maximum demand current Current protection X X
Minimum voltage (undervoltage) Voltage protection Vmin X X
Maximum voltage (overvoltage) Voltage protection Vmax X X
Voltage unbalance Voltage protection Vunbal X X
Reverse power Other protection rPmax X X
Minimum frequency (underfrequency) Other protection Fmin X X
Maximum frequency (overfrequency) Other protection Fmax X X
Phase rotation Other protection Φ rotation X –
Current load shedding Load shedding I Ished X –
Power load shedding Load shedding P Pshed X –

Minimum (Under) and Maximum (Over) Demand Current and Voltage Protection

Minimum/Maximum Protection Curves

Maximum Protection

Minimum Protection

Provides pickup and dropout values for alarm, contacts or tripping for current and voltage values. (There is no minimum for current.)

  • Pickup value (A) is set to activate an alarm or trip.

  • Pickup time delay (B) is set to start timing once the pickup value has been passed.

  • Dropout value (C) is set to deactivate the alarm and/or contact.

  • Dropout time delay (D) is set to start timing once the dropout value has been passed.

  • Minimum (under) voltage protection (Vmin) is activated when any line-line voltage is below the minimum voltage setting.

  • Maximum (over) voltage protection (Vmax) is activated when any line-line voltage is above the maximum voltage setting.

  • Vmin has a dropout value ≥ pickup value.

  • Vmax has a dropout value ≤ pickup value.

  • If current or voltage protection trips the circuit breaker, the circuit breaker cannot be reset until the current or voltage problem which caused the trip is corrected.

  • Ground-fault alarm on the 5.0P and 6.0P trip unit is based on true rms value of the ground current.

  • Do not set undervoltage protection below 80%.*

Current or Voltage Unbalance Protection

This protection applies to unbalanced values for the three-phase currents and voltages.

Current or Voltage Unbalance Protection

Reverse Power Protection (rPmax)

Reverse Power Protection

Reverse power protection protects alternators against absorption of the total actual power over all three phases in the event that a drive motor fails.

  • Reverse power protection applies a trip curve based on the total actual power value (A) over all three phases.

  • A time delay (B) starts timing if the total actual power of the three phases is not flowing in the defined direction and if it exceeds a reverse power threshold.

  • The power direction is defined during trip unit setup.

Minimum (Under) and Maximum (Over) Frequency Protection

Provides pickup and dropout values for frequency.

  • Pickup value (A) is set to activate an alarm or trip.

  • Pickup time delay (B) is set to start timing once the pickup value has been passed.

  • Dropout value (C) is set to deactivate the alarm and/or contact.

  • Dropout time delay (D) is set to start timing once the dropout value has been passed.

  • Fmin has a dropout value ≥ pickup value.

  • Fmax has a dropout value ≤ pickup value.

  • When system frequency is set to 400 Hz, the frequency protection is disabled.

Minimum/Maximum Frequency Curves
Minimum Protection Maximum Protection

Load Shedding

Load shedding does not trip the circuit breaker, but may be used to activate an alarm linked to an M2C or M6C contact (controlling non-priority network loads).

  • Load shedding is defined by a threshold and time delay:

    A—Activation threshold

    B—Activation time delay

    C—Dropout threshold

    D—Dropout time delay

  • Power load shedding depends on the flow direction set during trip unit setup.

  • Current load shedding is connected to the I2t or Idmtl long-time delay values.

  • Current load shedding cannot be activated if “Long-time OFF” rating plug is installed.

Load Shedding

Phase Rotation Protection

Protects the circuit when two of the three phases are reversed.

  • If one of the phases is down, this protection is inactive.

  • Options are ABC or ACB.

  • When system frequency is set to 400 Hz, phase rotation protection is disabled.

  • Do not use phase rotation protection to determine the loss of multiple phases in delta connected systems.

M2C and M6C Programmable Contact Kits

One or more alarms can be activated using an optional M2C or M6C programmable contact kit. The M2C contact kit provides two form A contacts with common neutral. The M6C contact kit provides six form C contacts. Each contact can be programmed through the trip unit for one alarm condition.

A 24 Vdc, 5 W auxiliary power supply is required for operation of trip unit/M2C or M6C contact kit combination.

NOTE: Trip unit and communication modules (BCM and CCM) must use separate power supplies. The M2C and M6C contact kits can share the trip unit auxiliary power supply.
Characteristics for M2C/M6C Programmable Contacts V A
Minimum Load 24 Vdc 100 mA
Breaking Capacity at a Power Factor (p.f.) of 0.7 240 Vac 5 A
380 Vac 3 A
24 Vdc 1.8 A
48 Vdc 1.5 A
125 Vdc 0.4 A
250 Vdc 0.15 A

M2C/M6C Wiring Diagrams
M2C: 24 Vdc power
supplied by trip unit 		M6C: external 24 Vdc
power supply required

Zone-selective Interlocking

Short-time and ground-fault protection can be interlocked to provide zone-selective interlocking.

Control wiring links several trip units in the distribution network and in the event of a fault, a trip unit will obey the set delay time only if receiving a signal from a downstream trip unit.

If the trip unit does not receive a signal, tripping will be instantaneous (with no intentional delay).

  • The fault is cleared instantaneously by the nearest upstream circuit breaker.

  • Thermal stresses (I2t) in the network are minimized without any effect on the correct time delay coordination of the installation.

Figure 16 shows circuit breakers 1 and 2 zone-selective interlocked.

  • A fault at A is seen by circuit breakers 1 and 2. Circuit breaker 2 trips instantaneously and also informs circuit breaker 1 to obey set delay times. Thus, circuit breaker 2 trips and clears the fault. Circuit breaker 1 does not trip.

  • A fault at B is seen by circuit breaker 1. Circuit breaker 1 trips instantaneously since it did not receive a signal from the downstream circuit breaker 2. Circuit breaker 1 trips and clears the fault. Circuit breaker 2 does not trip.

NOTE: Use I2t off with ZSI for proper coordination. Using I2t on with ZSI is not recommended as the delay in the upstream device receiving a restraint signal could result in the trip unit tripping in a time shorter than the published trip curve.
NOTE: Setting short-time delay (tsd) or ground-fault delay (tg) to the 0 setting will eliminate selectivity for that circuit breaker.

Zone-selective Interlocking

Metering

The MicroLogic P trip unit provides continuous metering of system values. Metered values can be checked using the graphic display screen or network system management software.

Trip Unit Testing

Trip unit LSIG functions can be tested using primary injection testing or secondary injection testing. Test trip unit using the appropriate test kit. (See Trip Unit Installation Check for more information.)

Operation Counter

The circuit breaker communication module is required to display the total number of times the circuit breaker has opened since initial installation and since the last reset and the day/time of last reset.

Indicator Lights

Overload Indicator Light

The overload indicator light (A) lights when the Ir long-time pickup level has been exceeded.

Overload Indicator Light
MicroLogic 5.0P Trip Unit MicroLogic 6.0P Trip Unit

Trip Indicator Lights

Trip Indicator Lights

A trip indicator light on the trip unit will light when the circuit breaker trips. If the trip unit has auxiliary power connected, the trip unit will display information about the trip.

The trip indicator light will remain lit until it is reset by pressing the reset button (A). Cause of trip should be corrected before resetting.

Ir trip indicator light (B) lights when long-time pickup (Ir) signals the circuit breaker to trip.

Isd/Ii trip indicator light (C) lights when short-time pickup (Isd) or instantaneous pickup (Ii) signals the circuit breaker to trip.

Ig trip indicator light (D) lights when ground-fault pickup (Ig) signals the circuit breaker to trip.

Ap self-protection/advanced-protection indicator light (E) lights when the advanced protection features cause a trip to occur, the trip unit overheats, the instantaneous override value is exceeded or a trip unit power supply failure occurs.

NOTICE
Hazard of equipment damage
If the circuit breaker remains closed and the Ap light remains lit after the reset, open the circuit breaker and contact the sales office.
Failure to follow these instructions can result in equipment damage.
NOTE: In cases where a number of causes may result in tripping, the LED signalling the last cause is the only one to remain on.

Test/Reset Button

Reset Button

The test/reset button (A) must be pressed after a trip to reset the fault information on the graphic display and clear the trip indicator light.

Graphic Display Screen

Graphic Display Screen

The graphic display screen (A) shows the trip unit settings and information. Navigation buttons (B) are used to display and modify items on the screen. Default display shows current levels.

Trip unit must be powered for graphic display screen to operate. The trip unit is powered if:

  • circuit breaker is on and has more than 150 V of load voltage on two phases (circuit breaker is closed or bottom fed).

  • the test kit is connected and on.

  • the 24 Vdc external power supply is connected.

  • an external voltage tap is installed and voltage of more than 150 V is present on two phases.

Contact Wear Indicator

The trip unit keeps track of the circuit breaker contact wear when a MasterPacT circuit breaker type is selected. The amount of wear on the circuit breaker contacts can be transferred when a trip unit is replaced. (External trip unit power supply is required.)

QR Code is a registered trademark of DENSO WAVE INCORPORATED in Japan and other countries.

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