Power Products (electrical) Frequently Asked Questions
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Question:
What is the difference between switching and linear power supplies?
Answer
The main difference is how they convert the AC line supply voltage to DC output voltage.
- Switching (switched-mode) power supplies first rectify the AC line supply, and then transform it.
Linear power supplies first transform the AC line supply, and then rectify it.
Switching power supplies have better efficiency, less heat loss, wider input voltage ranges, smaller size and weight, and are intended for general use in automation. Linear power supplies have less harmonics, and (if regulated) have more precise output regulation.
FAQ ID: 853
Question:
What is the difference between grounding and bonding?
Answer
Grounding is connecting your system to an earth ground. Bonding is connecting your system components to the grounding system. You can't have one without the other. If you do not have good bonding, then the chance of having poor low impedance pathways to ground will be present and will not allow for short circuit protection devices to function correctly. A poorly grounded system can also cause electrical noise to disrupt low voltage signals.
FAQ ID: 872
Question:
What is a ground loop?
Answer
The ANSI/IEEE dictionary calls it "potentially detrimental loop formed when two or more points in an electrical system normally at ground potential are connected by a conducting path such that either points are not at the same ground potential."
What does this mean?
It creates a pathway for current to flow. If one has a process control that works on a 4-20 ma signal, the added current from a ground loop could throw the reading off. This event can be catastrophic for some processes.
The two main methods of elimination are:
- Eliminate ground loops (which may not be possible because some control and instrumentation equipment require ground as a reference.)
- Signal isolation.
Each process or control system is different; it's always a case-by-case basis if it will be affected by ground loops.
FAQ ID: 873
Question:
Are there any standards for electrical installations?
Answer
The National Electrical Contractors Association (NECA) established the "Nation Electrical Installation Standards" (NEIS).
You can find more information from http://www.necanet.org/ or http://www.neca-neis.org/
FAQ ID: 874
Question:
Do the PS series power supplies have an isolated ground or is the negative leg of the output tied to ground either directly or indirectly by a passive or active component?
Answer
The output is isolated from the input, the -Vout is floating.
If you need to meet EMC emission standards, you would have to install external Y-capacitors from
- Neutral to PE (protective earth)
- Live to PE
- +Vout to PE
- -Vout to PE
FAQ ID: 939
Question:
Do the PS-series power supplies have a voltage adjustment pot? If so, where is it located?
Answer
The PS-series have a small pot that is located approx. 0.5" under the grill frame of the units. There is no separate hole, you will need to look at the unit from the top to see it. It is located to the left of the DC output terminals.
FAQ ID: 1184
Question:
Do you have SCCR (Short Circuit Current Rating) specifications for your power supplies?
Answer
According to UL508A Supplement SB Exception No 1, "Power transformers, reactors, current transformers, dry-type capacitors, resistors, varistors, and voltmeters are not required to have a short circuit current rating."
Power supplies are a type of power transformer and therefore do not require an SCCR rating.
FAQ ID: 1273
Question:
Can I get multiple voltages from your Hammond control transformers?
Answer
This is not recommended or supported by us or the manufacturer. It will void the warranty if done.
FAQ ID: 1298
Question:
How does the PSM24-BCM360S prevent deep discharge of the battery(batteries)?
Answer
The BCM monitors output voltage when the mains supply is off.
When the battery voltage drops to 20VDC +/- 0.5VDC the BCM shuts off the whole system until the mains power returns.
When mains power returns, the BCM turns the output back on and uses the surplus capacity from the power supply to recharge the battery.
FAQ ID: 1324
Question:
What are the mounting dimensions for the SD1 and SD2 series disconnects when using the shafts and handles?
Answer
The shaft will insert into the handle 16mm min to 18mm max.
The shaft will insert into the SD1 or SD2 10mm.
Measure the distance from the face of the SD1 or SD2 where the shaft will insert to the end of the disconnect handle where the shaft will be inserted and add 26 to 28 mm for the total shaft length.
FAQ ID: 1495
Question:
Can I use two 2 Rhino power supplies in parallel to get more current?
Answer
Although you can connect most of the Rhino series power supplies in parallel, you should always refer to the online data sheets to determine if the specific powers supplies in question can be used in parallel operation. However it is NOT recommended to use two supplies in parallel to increase the available power. The main reason is if one fails the other one will not be able to handle the load alone and will likely go into overload protection.
FAQ ID: 1503
Question:
Can I use two Rhino power supplies in parallel for redundancy?
Answer
In most cases you can connect two Rhino series power supplies in parallel, however you should always refer to the online data sheets to determine if the specific powers supplies in question can be used in parallel operation. Parallel operation requires the use of either a redundancy module like the PSP24-REM240S or the PSB60-REM20S or a decoupling diode with power ratings suitable for the application.
The Vishay VT4045C is good example of a decoupling diode and can be sourced from many online electronic component suppliers.
FAQ ID: 1504
Question:
Can we use two 24V power supplies connecting in series instead of one 48V power supply?
Answer
YES, however care should be used to make sure the required output current not exceed maximum current rating on the smallest power supply in the circuit.
For example:
(PS1 = 24vdc @ 10amps) + (PS2 = 24vdc @ 12amps) = 48vdc @ 10amps
It is also recommended that decoupling diodes with power ratings suitable for the application be used on the outputs of both supplies in the event the power supplies fail to power up at the same time or the load is shorted to protect against reverse voltage being applied to the output terminals.
The Vishay V20100S-E3/4W is good example of a decoupling diode and can be sourced from many online electronic component suppliers.
FAQ ID: 1505
Question:
Can I use my retired Eaton WMZS/WMZT series accessories with my new FAZ/FAZ-NA series Supplementary protectors and Miniature circuit breakers?
Answer
The WMZT circuit breaker busbars and busbar accessories are a direct cross to the FAZ-NA busbar system (ZSVUL16 series). The busbar systems will work interchangeably.
Eaton does not recommend the mixing of the other accessories such as WMZS/WMZT and FAZ/FAZ-NA auxiliary contact blocks and shunt trips.
FAQ ID: 1536