
CHAPTER 6: SETPOINTS PROTECTION ELEMENTS
MM300 MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL 6–43
VT Fuse Fail
Range: Disabled, Alarm, Trip
Default: Trip
This setpoint selects the fuse failure action.
6.3.4 Sensor protection
6.3.4.1 RTD protection
The MM300 can support up to six 100-R RTDs, each of which may be configured to have a
trip temperature and an alarm temperature. The alarm temperature is normally set slightly
greater than normal running temperature, and the trip temperature is normally set at the
insulation rating. Trip voting has been added for extra security in the event of RTD
malfunction. If enabled, a second RTD must also exceed the trip temperature of the RTD
being checked before a trip will be issued. If the RTD is chosen to vote with itself, or OFF, the
voting feature is disabled.
The following table shows the RTD resistance versus temperature. RTDs configured as
stator types are also used by the thermal model for determining the RTD bias.
Table 4: RTD temperature vs. resistance
Temperature Resistance (in ohms)
°C °F 100 Pt
–50 –58 80.31
–40 –40 84.27
–30 –22 88.22
–20 –4 92.16
–10 14 96.09
0 32 100.00
10 50 103.90
20 68 107.79
30 86 111.67
40 104 115.54
50 122 119.39
60 140 123.24
70 158 127.07
80 176 130.89
90 194 134.70
100 212 138.50
110 230 142.29
120 248 146.06
130 266 149.82
140 284 153.58
150 302 157.32
160 320 161.04
170 338 164.76
180 356 168.47
190 374 172.46
200 392 175.84
210 410 179.51
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