Securitron PS-1M_Series User Manual

Page 2

PN# 500-20400

Page 2

Rev. D, 08/11

FIG. 1 BATTERY PACK SELECTION

MIN

1 HR

2 HR

4 HR

8 HR

16 HR

24 HR

48 HR

72 HR

UL STD.

150 MA

300 MA

500 MA

4 AH

8 AH

12 AH

8 AH

12 AH

16 AH

N/A

BACKUP TIME DESIRED

"MIN" TIME REFERS TO FACILITY USING EMERGENCY GENERATOR WHERE THE
BATTERIES ARE ONLY REQUIRED TO OPERATE THE SYSTEM
FOR UNDER 3 MINUTES UNTIL THE GENERATOR TAKES OVER

U.L. STANDARD REQUIRES 4 HOURS OF BATTERY OPERATION FOLLOWED BY
A 24 HOUR RECHARGE PERIOD AND THEN A SECOND 4 HOURS OF OPERATION

BATTERIES MUST BE SEALED LEAD ACID OR GEL CELL TYPES.

DRY CELLS WILL NOT RECHARGE AND WILL BE DAMAGED.

THIS CHART IS ONLY VALID IF BATTERIES ARE OPERATED

AT ROOM TEMPERATURE. IN A COLD ENVIRONMENT, CAPACITY IS REDUCED.

BATTERIES SHOULD BE REPLACED AFTER 5 YEARS OF USE.

750 MA

12 AH

16 AH

20 AH

RRE

DRA

CHART TO DETERMINE SIZE OF BATTERY PACK

N/A

The components utilized on the unit for battery charging function for battery packs up to 20 amp
hours in capacity whether 12 or 24 volts. Note that certain long backup times are not
achievable with the maximum size of the battery packs (“N/A” appears in the chart). Consult
the battery pack chart to calculate the correct battery pack based on desired backup time and
the current drawn by the load. Note that for proper battery charging the power supply

must be set at 27 volts in the case of a 24 volt system, and 13.5 volts in the case of a 12
volt system. The boards are capable of this adjustment and if it is not made, the batteries will
not hold their full capacity nor their normal operating life, and may be damaged. Also note
that batteries must be replaced at least every 5 years as that is their maximum
operating life.

3.4 CIRCUIT POLYSWITCH
The boards are internally protected against overloads (they will shut down). A DC short,
therefore, cannot damage the board but still will cause problems as the load will be shut off. On
the other hand, if batteries are used, they will switch into the short when the board shuts down

and will supply a tremendous amount of current into a short which is capable of melting wire
insulation. To protect against a short circuit when batteries are being employed, a 2.5 Amp DC
Polyswitch breaker is provided. The Polyswitch functions as an automatic circuit breaker. If it
receives an overload, it rapidly cuts the current down to a small leakage current (about 100
mA). If this happens there is a reset procedure. All current must be removed from the
Polyswitch for a period of 10 seconds. You do this by simply disconnecting the wire from

the “+” or “-” terminal. If, for example, a short circuit appeared which tripped the Polyswitch
and you corrected the short but did not disconnect the wire from the “-” terminal, the Polyswitch
would “see” the normal load and would continue to block current flow until reset in the manner
just described.