Page 90
I.L. 17562
PR 0.3 Effective 8/99
SECTION 9. APPLICATIONS AND SETTINGS
9.0 General —
This section is a supplement to Section 5, giving more engineering and
application guidance for particular functions and setpoints.
Use this data in conjunction with Section 5 and Table 4.3, to develop setpoints for the MP-3000,
as well as making appropriate wiring design. Note that particular setpoints are designated as
PnLm
, where
Pn
is the page number and
Lm
is the line number of the particular setpoint in
Table 4.3, and in the page-line-value scheme of accessing setpoints on the front panel of the
MP-3000.
9.1 Motor Protection —
The MP-3000 protects the motor, starter, and load in the following
ways:
•
Stator and rotor thermal protection by modeling of heating and cooling effects, including
heating by negative sequence currents.
•
Stator overtemperature protection by direct measurement (with optional URTD module).
•
Instantaneous overcurrent protection for faults.
•
Ground fault protection.
•
Phase reversal protection.
•
Phase unbalance protection.
•
Motor bearing and load bearing temperature protection (with optional URTD module).
•
Jam protection.
•
Underload protection.
•
Incomplete sequence protection (missing status feedback from load).
•
Trip-bypass output for failure of contactor to interrupt current after a trip.
9.1.1 Thermal Modeling and Overload Protection without RTDs —
Refer to Figure 9.1. The
motor overload protection function, called the I
2
T algorithm, calculates the rotor and stator
temperature based on effective heating current, integrated over time. Positive and negative
sequence current magnitudes are calculated in separate accurate algorithms. The effective
heating current is the sum of the positive and negative sequence currents, with a heavy
weighting factor on the negative sequence contribution. This models the disproportionate rotor
heating effect of the negative sequence current (see
Motor Thermal Protection Basics
,
Section 8). Certain harmonic currents such as the 5
th
and 11
th
also produce the same heating
effects as fundamental-frequency negative sequence current; this harmonic heating effect is also
measured and modeled.
The temperature rise caused by current flow is modeled with a thermal accumulator or bucket
whose size or capacity is derived from motor nameplate data entered as setpoints. The flow of
effective heating current into the bucket causes it to fill. Cooling is modeled by a gradual
emptying of the bucket. The setpoints which influence the heating and cooling models are:
•
Full-load amperes (FLA, P1L1)
•
Locked-rotor current (LRC, P2L2)
•
Maximum allowable stall or locked-rotor time (LRT, P1L3)
•
Ultimate trip current (UTC, P1L4), which is usually service factor times 100 percent.
The MP-3000 thermal bucket fills and proceeds towards a trip only when the effective heating
current is above the ultimate trip current setting, P1L4. The modeling is based on an ambient
temperature of 40 degrees C. A programmable I2T alarm I2TA, P4L2 informs the user when the
bucket reaches the user-set level between 60 percent and 100 percent full.
Without manual process load reduction, automatic process load shedding (see 9.1.5), or other
remedial action after an alarm, the relay eventually trips and displays the message LRC/I2T
Summary of Contents for MP-3000
Page 18: ...Page 18 I L 17562 PR 0 3 Effective 8 99 Figure 4 1 MP 3000 Pushbuttons...
Page 19: ...I L 17562 Page 19 PR 0 3 Effective 8 99 Figure 4 2 MP 3000 LED Indicators...
Page 72: ...Page 72 I L 17562 PR 0 3 Effective 8 99 Figure 6 1 Panel Cutout Dimensions...
Page 73: ...I L 17562 Page 73 PR 0 3 Effective 8 99 Figure 6 2 Faceplate Dimensions...
Page 74: ...Page 74 I L 17562 PR 0 3 Effective 8 99 Figure 6 3 MP 3000 Case Depth Dimensions...
Page 75: ...I L 17562 Page 75 PR 0 3 Effective 8 99 Figure 6 4 Universal RTD Module Mounting Dimensions...
Page 76: ...Page 76 I L 17562 PR 0 3 Effective 8 99 Figure 6 5 Rear Panel Terminals...
Page 78: ...Page 78 I L 17562 PR 0 3 Effective 8 99 Figure 6 7 Typical ac Supply and URTD Wiring...
Page 79: ...I L 17562 Page 79 PR 0 3 Effective 8 99 Figure 6 8 Alternatives for Discrete Input Wiring...
Page 80: ...Page 80 I L 17562 PR 0 3 Effective 8 99 Figure 6 9 RTD Wiring to URTD Module...
Page 100: ...Page 100 I L 17562 PR 0 3 Effective 8 99 Figure 9 1 Rotor Temperature Tracking...
Page 101: ...I L 17562 Page 101 PR 0 3 Effective 8 99 Figure 9 2 Motor Protection Curve...
Page 102: ...Page 102 I L 17562 PR 0 3 Effective 8 99 Figure 9 3 Underload Jam Protection Curve...
Page 104: ...Page 104 I L 17562 PR 0 3 Effective 8 99 Figure 9 5 Motor Protection Curve Example with RTDs...
Page 105: ...I L 17562 Page 105 PR 0 3 Effective 8 99 Figure 9 6 Motor Start and Run Cycles...
Page 109: ...I L 17562 Page 109 PR 0 3 Effective 8 99 P5L8 40 Incomplete Sequence time 1 60s OFF 1 240s...