American Power Conversion LVD400, LVD500, LVD600 Circuit Description, General, Dc Connections

SECTION 3: CIRCUIT DESCRIPTION

GENERAL

1With reference to the circuit diagram in Appendix B, the units consist of a contactor and control circuitry to connect and disconnect the input voltage to and from the output. The units are typically used in line with a positive earth power system, between for example a power cubicle (input) and a battery (output).

DC CONNECTIONS

2The input voltage on the negative input terminal is fed via fuse FS1 to the contactor BC1, which is normally closed, directly to the output at the negative output terminal. The positive common output cable from the external power system is not connected to the units (only an auxiliary input, capable of carrying a light current to power the LVD PCA is required).

LOW VOLTAGE DISCONNECTION

3If the input voltage decreases to 42.5 V the contactor is de-energised and the contacts opened via a signal from the LVD PCA, which disconnects the output. The contactor is energised and the contacts closed, reconnecting the output when the input voltage increases to 51.5 V.

4The remote contacts change over when the contactor is de-energised with the N/C and C terminals (terminals 4 and 5) on TB1 being opened and the N/O and C terminals (terminals 5 and 6) being closed.

MANUAL OVERRIDE

5The keyswitch provides a manual override to de-energise the contactor irrespective of the input voltage, when set to the OPEN position.

REMOTE LOOP CONTACTS

6The REMOTE LOOP contacts on TB1 terminals 1 and 2 are normally linked and if the link is broken the contactor is de-energised and disconnects the unit from the external equipment. When installed, this link can be replaced by a link to a remote location which is broken when an emergency occurs.

Page 6 of 20 Text artwork 990-9030 Rev. A. Equipment Handbook for the Low Voltage Disconnectors series