Xantrex Technology SW Series Overvoltage Protection for the Battery in Sell Mode, Solar Array

OPERATION

OVERVOLTAGE PROTECTION FOR THE BATTERY IN SELL MODE

Normally, the inverter will regulate the charging process of the battery by selling excess power into the utility grid. The battery will receive a three-stage charge routine as previously described. If the utility grid is not available (due to an outage or tripped AC input circuit breaker, etc.) or if the inverter shuts off, then the inverter is not able to sell the excess power and the battery voltage will not be regulated, resulting in possible overcharging of the battery.

Therefore, a separate control is required to provide overvoltage protection for the battery when an outage has occurred. The AUX Relays in the SW Series Inverter/Charger are designed to control an externally connected power relay that would disconnect the solar array and stop the charging process. The voltage and hysteresis (difference between opening and closing voltage) are both adjustable. The external relay can be either a standard mechanical type or a mercury displacement type, depending on the voltage and current required. The mercury displacement type relay is usually required when the system voltage is 48 VDC or if the current of the solar array exceeds about 20 amps. Multiple relays can be used if the solar array is divided into several source circuits (do not parallel relays for higher current). Another option is to use a charge controller such as the Trace™ C40. For more on the C40 MULTI-FUNCTION CONTROLLER, see page 129.

A typically wiring configuration for this overvoltage protection is as follows: SOLAR ARRAY

This circuit does draw a small amount of power all of the time to power the coil of

the relay. Other circuits are possible but may have other drawbacks. This circuit +P -Nprovides protection against overcharging the batteries.

		120VAC	NORM.
			OPEN
		COIL
			RELA
	AC OUTPUT - NEU	-N
	AC OUTPUT - HOT
5 AMP	SW - SERIES	+P
FUSE	INVERTER
	AUX RELAY 9 COM.
	AUX RELAY 9 N.C.
		+P	-N
		BATTERY BANK

Figure 30, Overvoltage Protection for Battery

AUX RELAYS

Three voltage-controlled relays are provided to simplify installations that have battery voltage related tasks to perform. They are single pole double throw, five amp relays. Both the normally closed and normally open contacts are available for each relay. The operation of the relays are individually controlled and adjustable via the user menu. The battery voltage at which each of these relays are activated (SET RELAY 9, 10 or 11 VOLTS DC) and the number of volts by which the battery voltage must drop before the relay is de-activated (R9, R10 or R11 HYSTERESIS VOLTS DC) are both individually adjusted for each relay. The three AUX Relays operate independently of the inverter or charger. For location and wiring information on the AUX Relays, see the AUXILIARY AND GENERATOR CONTROL RELAY section on page 14.

CAUTION: These relays are not intended to directly control a load or charging source - rather they can be used to send a signal or operate the coil of another higher amperage device which does the actual switching of the power. A fuse rated at 5 amps or less should be included to protect each of the relays. Damage to these relays from overloading is not covered by warranty and requires the inverter to be returned to a repair center. This also applies to the generator control relays.

 2001 Xantrex Technology, Inc.	Telephone: 360/435-8826	SW Series Inverter/Charger
5916 - 195th Street N. E.	Fax: 360/435-2229	Part No. 2031-5
Arlington, WA 98223	www.traceengineering.com	Rev. C: February 2001

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