Emerson MPR25, MPR15 Series user manual Operation, Test feature, Signal connections

Low voltage disconnect 71

Operation

The battery voltage is monitored by the low voltage disconnect and low voltage alarm circuit (LVA). When the voltage drops to approximately -47 V DC, the LVA LED lights up and the alarm is extended to the terminal block.

When the battery voltage drops to the low voltage disconnect level, the contactor opens, disconnecting the load from the battery. This turns the LVD LED ON and activates the low voltage disconnect alarm. When the battery voltage rises by approximately 8 V (adjustable) above the release level, the load is reconnected to the batteries and the alarm is cleared.

The LVD potentiometer sets the level at which the load disconnects and the LVDR potentiometer sets the level at which the load reconnects. Test jacks (TP1 and TP2) provide the plant discharge voltage when the 'TEST' switch is set to NORMAL.

Test feature

The internal test feature facilitates the verification of the low voltage disconnect, reconnect, and low voltage alarm circuitry, without disconnecting the load.

When the panel switch is set to 'Test/Bypass' a ground signal is applied to lock the LVD contactor and the 'TEST' potentiometer is connected in series with the control circuit. Varying this potentiometer will affect the voltage senses by the LVD and LVA detectors. This test voltage can be verified at test jacks TP1 and TP2.

Signal connections

The signal connections are shown in Figure 26 of this manual (see the “Operation” chapter of this manual for the installation of the low voltage disconnect unit).

25A Switch Mode Rectifier NT5C06B / C Installation and User Manual