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©
2017 Sensata Technologies
Operation
-0.75
-0.6
-0.45
-0.3
-0.15
0
0.15
0.3
0.45
0.6
0.75
0
5
1 0
1 5
2 0
2 5
3 0
3 5
4 0
4 5
5 0
Temperature reading from BTS (in degrees)
Temperature Compensation using BTS
0C
32F
5C
41F
10C
50F
45C
113F
30C
86F
40C
104F
35C
95F
25C
77F
20C
68F
15C
59F
50C
122F
48VDC units
+3.0V
+2.4V
+1.8V
+1.2V
+0.6V
No Change
-0.6V
-1.2V
-1.8V
-2.4V
-3.0V
Change to battery charging voltage
no BTS
connected
24VDC units
+1.5V
+1.2V
+0.9V
+0.6V
+0.3V
No Change
-0.3V
-0.6V
-0.9V
-1.2V
-1.5V
Figure 3-4, BTS Temperature to Charge Voltage Change
3.2.2 Transfer Time
While in Standby mode, the AC input is continually monitored. Whenever AC power falls below
the VAC dropout voltage (80 VAC per leg – default setting), the inverter automatically transfers
back to Inverter mode with minimum interruption to any connected appliances—as long as the
inverter is turned on. The transfer from Standby mode to Inverter mode occurs in approximately
16 milliseconds. While the MS-PAE Series is not designed as a computer UPS system, this transfer
time is usually fast enough to hold them up. However, the
VAC Dropout
setting has an effect on
the ability of the loads to transfer without resetting. The lower this setting, the longer the effective
transfer will be and therefore, the higher the probability for the output loads to reset. This occurs
because the incoming AC voltage is allowed to fall to such a low level that when the transfer does
occur (in addition to the relay transfer time) the voltage on the inverter’s output has already fallen
to a low enough level to reset the loads.
The disadvantage of a higher
VAC Dropout
setting is that smaller generators (or large generators
with an unstable output) may nuisance transfer. This commonly happens when powering loads
that are larger than the generator can handle—causing the generator’s output to constantly fall
below the inverter’s input VAC dropout threshold.
Info:
When switching from Inverter mode to Standby mode, the inverter waits
approximately 15 seconds before transferring to ensure the AC source is stable.
3.3
Battery Temperature Sensor Operation
The plug-in Battery Temperature Sensor (BTS) is used to determine the temperature around the
batteries. This information allows the multistage battery charger to automatically adjust the battery
charge voltages for optimum charging performance and longer battery life.
When the BTS is installed, the charge voltage while in the Bulk, Absorb or Float charge mode
will either increase or decrease if the battery temperature is greater or lower than 77°F (25°C).
If the temperature around the BTS is below 77°F (25°C) the charge voltage increases and if the
temperature around the BTS is higher than 77°F (25°C), the charge voltage decreases. The farther
the temperature change from 77°F (25°C), the greater the change in the charging voltage. See
Figure 3-4 to determine how much the charge voltage changes (increases or decreases) depending
on the temperature reading of the BTS. For example, the nominal absorb charge voltage for a
fl
ooded battery at 77°F (25°C) on a 24-volt model is 29.2 VDC. If the battery temperature is 95°F
(35°C), the absorb charge voltage would decrease to 28.6 VDC (29.2 nominal – 0.6 change).
If the temperature sensor is NOT installed, the charge voltages will not be compensated and the
battery charges at a temperature of 77°F (25°C). Without the BTS installed, the life of the batteries
may be reduced if they are subjected to large temperature changes.
Info:
The temperature to voltage compensation slope the BTS uses is 5mV/°C/Cell
from 0 to 50°C.
