AC Branch Circuit Limitations

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This section helps you find if you must make any changes to your facility to use Sun products. When configuring and installing your Sun products, you should be aware of AC branch circuit current limitations imposed by local electrical codes.

Individual products or groupings of Sun products may exceed the limitations dis-cussed in this section. Make sure not to exceed the local electrical code's limita-tions when configuring these Sun products.

A fully configured logic pedestal will draw 12 Amps in the 100 to 120 volt operating range. Treat the logic pedestal as fully configured so that site planning will allow for upgrades.

U.S. and Canadian electrical codes allow only an 80% load on any given branch circuit. The 80% derating limit does not apply in other countries. Make sure that the total current does not exceed the branch circuit limits for your installation.

Check the local electrical codes to be sure you do not overload a circuit.

The cords will plug into 15 amp (maximum load is 12 amps) and 20 amp (max-imum load is 16 amps) outlets in the U.S. Other areas have typical branch circuit ratings of 10, 13, 15, or 16 amps depending on the country.

A number of outlets may be connected to a single branch circuit. Ask a facilities manager to be sure for your installation. Many electricians include this informa-tion inside circuit breaker panels. Addiinforma-tional circuits may be required to handle the monitor and/or expansion pedestal.

The U.S. National Electric Code (sections 21O-22[c], 210-23, and 64S-2[a]) lim-its the total current of connected devices to 80% of the AC branch circuit's max-imum capacity averaged over a three hour period. For the United States, the standard AC branch circuit is 15 amps at 120 volts AC (V AC). Table 5-1 presents all of the different 120 V AC branch circuits that may be used by Sun equipment and their maximum permissible current loads in the U.S.

Table 5-1 Circuit Breaker and Maximum Current

Impact of Non-Sun Devices on the Same AC Branch Circuit

Sun Product Power Limits

Circuit Breaker Rating

For areas outside the United States, contact the agency responsible for local electrical codes about specific infonnation on local AC branch circuit limitations.

Make sure that the total current load of the branch circuit to which Sun equip-ment is to connected does not exceed the figures in the above table. In some cases, the logic enclosure alone will require its own branch circuit

You must also calculate the volt amp values for non-Sun electrical devices on the same branch circuit Some non-Sun device calculations are as follows.

o For a lamp with a 100 watt light bulb, the volt amp equivalent is 100 volt amps because the light bulb is a purely resistive device.

o For a small electrical office appliance such as an air purifier, consult the manufacturer's manual or look for a rating that is probably located on the outside of the device close to where the power cord enters the casework. If the rating is in amps and volts, just multiply the two values together. If the only value available is in watts, multiply the watts value by 1.67 to be on the safe side. The 1.67 value is the reciprocal of a 0.60 power factor (usually the worst-case rating any product has).

All Sun 6-slot and 12-slot products are rated to work without failing to voltages as low as 90 V AC on a 120 V AC branch circuit At the lowest working voltage, the current draw increases to maintain the power applied to the unit at the higher voltage. Since 15 amps at 90 V AC is about equal to 12 amps at 120 V AC, a 15 amp line fuse is used for these products. Sun power supplies are rated for opera-tion between 47Hz to 63 Hz.

For each type of AC branch circuit, Table 5-2 presents the maximum DC loads in watts that are for each Sun product when no other electrical loads are connected to the same AC branch circuit Variations between the products are the result of power supply design differences (for instance, Sun-3/160 vs. Sun-3/260).

CAUTION Phase currents into many Sun products (or any other products using switch-ing power supplies without power factor correction) do not cancel in the neutral of a three-phase distribution system. This can result in the neutral carrying excess currents when the distribution system is heavily loaded with switching power supply loads. Contact your facilities manager or a qualified electrician if you suspect this problem might occur.

Table 5-2 Maximum AllowedLoad* (DC WATIS) For Standard Nominal VAC Levels Sun Product Maximum Rated Maximum Allowed Load* (DC WAITS)

Power Supply Output For Standard Nominal VAC Levels (DC watts)

l00VAC 120VAC 200VAC 208VAC 220VAC 240VAC

3/50/60 (before 12/15/88) 100 100 100 100 100 100 100

3/50/60 (after 12/15/88) 116 116 116 116 116 116 116

3/80 3/150 3/160

3/260/280/480**

3/470 3/480tt

85 85 85 85 85 8S 85

575 575 575 575 575 575 575

825 546 655 546 568 600t 655t

850 600 690* 600 624 660 690*

925 925 925 925 925 925 925

925 690* 690* 690* 690* 690* 690*

NOTES * "Maximum allowed load" values may be less than "maximum rated power supply output" values due to AC line current limitations.

t VAC values shown represent nominal line voltage values (+/-10% variation is assumed). 100 VAC and 200 V AC are for Japan. 120 V AC is for North Amer-ica. 220 V AC is for continental Europe. ·240 V AC is for the United Kingdom, Ireland, and Australia. Consult your local sales office for information in other areas.

* Because of cooling constraints of the logic pedestal, no more than 690 Wdc is allowed.

** Systems shipped before 10/1/89 tt Systems shipped after 9/30/89

When detennining DC power requirements for your specific configuration, you must include backplane and cooling fan(s) loads. Table 5-3 presents DC power requirements for all Sun provided options.

Early European Sun-3/160 products were shipped with a 5 amp 250 VAC line fuse. If your unit has a 5 amp fuse and more DC power is required, a 6.3 amp fuse may be installed to allow for an additional power capability. Contact your local Sun Customer Service Office for infonnation on the fuse.

Beside checking that the overall DC wattage capacity of the power supply is not exceeded, use the following table to make sure that none of the individual DC output current ratings for the power supply are exceeded when configuring your system. To calculate your needs, use the values in Table 5-3.

Table 5-3 DC Output Current Ratings for Configurable Sun Products DC Output Capacity

Output 3150 &3160 3180 31150 3116012601280·· 3126012801480··· 31470

+ 5.0 15/20 amps* 12 amps 100 amps 120 amps 150 amps 150 amps

- 5.2 2.0/1.0 amps* - 8 amps 10 amps 15 amps 15 amps

+12.0 1.3/0.5 amps* 0.4 amps 3.0 amps 15 amps 15 amps 15 amps

+12.0MTR 2.0 amps 2.0 amps

- -

-12.0 n/a 0.1 amps 1.5 amps 5 amps 10 amps 10 amps

NOTE

*

** For systems shipped before 10/1/89

3/50/60/140/150 and Sun-4/110/150

5.7. Safety Agency