Ground-Fault Display. ABB MicroVersaTrip Plus(tm) and MicroVersaTrip PM (tm) Trip Units

MicroVersaTrip Plus™ and MicroVersaTrip PM™ Trip Units

Chapter 4. Status Mode

Ground-Fault Display

When a ground-fault trip occurs, the display illustrated in Figure 62 appears. The fault current is displayed in units of xCT, the breaker CT sensor rating.

Multiply the sensor rating of the breaker by the displayed fault current multiplier to obtain the groundfault current at trip.

Shunt Trip and Undervoltage Release Trip

Displays (RMS9D Series Trip Units Only)

When a Power Break ®II breaker trips due to the

Shunt Trip, Shunt Trip with Lockout, or

Undervoltage Release, the display indicates the trip with a flashing target, as illustrated in Figure 64. The indications

ST

and

UVR

appear for Shunt Trip and

Undervoltage Release trips, respectively. Note that the

FAULT

segment does not display, since the trip originated external to the breaker and may not represent a true fault condition.

Figure 62. Trip Unit status display for ground-fault trip.

Protective-Relay Fault Display

After a protective-relay trip, the display indicates

FAULT

with a target for the type of relay that initiated the trip. This is illustrated in Figure 63 for an overvoltage trip. The targets for the five protective relays are listed in Table 18.

Figure 63. Trip Unit status display for protective-relay trip.

Figure 64. Trip Unit status display for Undervoltage Release trip.

Clearing the Trip Information

Since trip information is stored in nonvolatile memory, the Trip Unit continues displaying the trip information until it is manually cleared or a new trip occurs. After the trip information has been recorded or reviewed, it can be cleared with the keypad. With the Trip Unit in Status mode, hold down the

VALUE key and press the

SELECT

key. The trip information is then cleared and the display reverts to

STATUS OK

, as in Figure 56.

C od e P otttteee cttttiiiivvvveee R ellllaa

∆

V Voltage unbalance

∆

I Current unbalance

V < Undervoltage

I

I

V > Overvoltage

Power reversal

Table 18. Trip Unit display targets for protective relays.

Trip Operations Counter Display

Trip operations counters record the total number of overcurrent trips. To review any of the trip operations counters while in Status mode, press the

SELECT key until the desired count appears. Figure 65 illustrates a typical trip operations counter display.

This example indicates that there have been three long-time trips on this breaker since the counter was last reset.

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