Frequency Converter

Whether you need a 1-phase or 3-phase frequency converter, looking to convert between 50Hz and 60Hz or require a converter capable of handling frequencies up to 400Hz, ATO online store has you covered. Our extensive range of frequency converters ensures that you can find the right solution for your specific requirements.

In addition to our wide selection of converters, we're committed to providing comprehensive pre-sales and after-sales technical support. We've collected some frequently asked questions from customers about frequency converters, including wiring, installation, operation and troubleshooting. Before reaching out to our expert engineer service team, we encourage you to explore these resources to enhance your understanding and usage of frequency converters.

Frequency Converter Pre-Sales Support

1. 75kVA 3-Phase Frequency Converter

Q: For your 75kVA 3-phase frequency converter, the 104.2A is inrush current or nominal current? The in-rush current duration for my application is less than 0.5 seconds and the nominal is ~11 amps. Would I still require a 75kVA unit?
A: The 104.2A is the max inrush current the frequency converter can handle, so, even if the in-rush current duration for your application is less than 0.5 seconds, the recommended converter would be 75kVA as listed below. In sizing the most advanced and high-efficiency solid-state converter, we size it based on your equipment inrush current Not rated current.

2. Sub-Panel Connection with Frequency Converter

Q: Can we run your frequency converter to a sub-panel from the converter?
A: Yes, sure! The converter input/output terminals are hard wire "free terminals", so you can connect any number of loads or a sub-panel.

3. Neutral Line in Frequency Converter

Q: Does your frequency converter input terminal or output terminal have a neutral line?
A: For converter input "your supply" configuration, it can be 3-phase, Wye (L1, L2, L3 + N, G) or 3-phase, Delta (L1, L2, L3 + G), which one do you need?

1. If the neutral is required "Wye", your supply must have this terminal.
2. If your supply is 3 3-phase 4 wire (3 wire for hot conductor, and the fourth one is for neutral), then you have to use 3-phase, Wye (L1, L2, L3 + N, G) converter config.

The converter output will be (L1, L2, L3 + N, G), and it works for both Delta and Wye configurations, we mean neutral can be sued or not, it's up to you. Does your frequency converter input terminal or output terminal have a neutral line?

4. Converter Output Adjustment and Interference Issues

Q: When you adjust the output you only have the voltage and frequency you choose on one output right? What I mean is that if you set the output to 60Hz there is no other output on 400Hz. The reason I ask is that I am concerned about interference since we will locate the transformer in an equipment room. Is there any risk of interference from your equipment?
A:

1. Yes, you only have the voltage and frequency you choose on one output. So, it's one adjustment for voltage and frequency in the ranges (40-499.9Hz) & (0-150V).
2. No risk of interference, just keep about a 1-meter space distance around the converter.

5. 1/3 Phase Frequency Converter Programming

Q: Does your frequency converter require programming?
A: Complicated programming is not required. As you said, it's just to adjust the converter outputs for the required frequency and voltage, No more.

6. 10kVA Frequency Converter

Q: Considering purchasing the 10kva frequency converter. I have a delta system for the input. Will the output be a Wye with a neutral?
A: Yes, that is correct. Although the converter input (your supply) is Delta, the converter output will be Wye with a neutral.

7. Delta configuration in Frequency Converter

Q: For your Frequency Converter; Is this 480V (+/- 10%) correct for Delta configuration, because the facility is running consistently between 490 to 500 V?
A: Yes, 480V (+/- 10%) is correct for Delta configuration, and 490 to 500V is okay with no problem at all.

8. 50Hz to 60Hz Converter CE Certification

Q: Is your 50Hz to 60Hz frequency converter CE-certified? What are the quality documents furnished with product supply?
A: Yes, our frequency converter is CE-certified. For quality documents, we provide a factory calibration certificate during the converter testing stages.

Guide to Choosing the Right Frequency Converter

Based on the customer's needs, ATO is dedicated to recommending the most suitable frequency converter. We thoroughly understand the customer's requirements and provide precise recommendations tailored to their specific needs. Whether you require high performance, efficiency, energy-saving, or other specific requirements, we will customize solutions according to your preferences. Before making a purchase decision, feel free to refer to the information table below we have collected and compiled, or the ATO frequency converter buying guide. This information and data may match your needs and will help you better understand the available frequency converter options and make wiser choices.

Customer Needs	Recommended Converter
Accept standard US 110/120V 60 Hz power and output 230V 50 Hz power for use with a 200-W instrument with a Singapore (Type G) power plug.	HZ-60-1101
Input power in Spain is 380VAC–50Hz, Output: 200A of 460VAC–3 PH, 60Hz	HZ-50-33200
Input: 440 volts, 3 phase, 60Hz, Output: 200 volts, 3 phase 400 Hz, Load starting current: 15A	HZ-50-3310
Convert 1-phase, 208V, 60Hz to 1-phase, 230V, 50Hz, to run 30A UK motor with a drive	HZ-50-1110
Input: 220V/60 Hz, Output: single-phase 220V/50 Hz. Support the power needed for a calibration lab device that draws peak current (approximately 17 amp).	HZ-50-1105
Input: 1 phase, 240 VAC, 50 Hz; Output: 1 phase, 240 VAC, 60 Hz. Pumps and other motors for the unit are on VFDs. Inrush Current is 70A.	HZ-50-1120
100kVA converter 380VAC 50Hz (L1, L2, L3, N, G) to 440Vac 60Hz (L1, L2, L3, N, G), have a 65kW (with VFD).	HZ-50-33100
Input: 480 VAC 60Hz, Output: 400 VAC 50Hz, Load: 10A (Approx 7A electronics, and the remaining 3A is for different small motors)	HZ-50-3320
60 KVA, change 3 phase 480V 60Hz to 3 phase 400V 50Hz	HZ-50-3375
Convert from 3 3-phase 400V 50Hz grid supply in Denmark to a series of equipment operating at 3-phase 208V 60Hz, the total amperage for the main electrical panel supplying the equipment will be 60amps.	HZ-50-3345
Change 400V 3 phase 50Hz to 230V 3 phase 60Hz and the capacity must be 40 kW and 100 amps.	HZ-50-3360
12kVA, change 3 phase 400V 50Hz to 110V 3-phase 60Hz converter	HZ-50-3315
Input: 240VAC, Output: 120VAC, 60Hz, 4 amp, Load: Oxygen Concentrated	HZ-50-1103
Convert from 240V 50hz to 120V 60hz, for some music equipment, a 5-watt amp, a 15-watt amp and a series of guitar pedals.	HZ-60-500W
Power: 1000VA, Input: 110V 60Hz; Output: 220V 50Hz	HZ-50-1102
Input: 380V/50Hz/3-Phase, Output: 460V/60Hz/3-Phase, Capacity: 150 KVA	HZ-50-33150
120V 60Hz to 240V 50Hz, 30~50 amp range, for testing the systems on the boats.	HZ-50-1120
Input Voltage: 220VAC 50 Hz, Output Voltage: 1-115 VAC (Adjustable Voltage Range), Output Frequency: 400Hz, Output Power: 500-1000W	HZ-50-1115

Frequency Converter After-Sales Support

1. 400Hz Frequency Converter Maintenance Advice

Q: I have a technical question regarding the 400Hz frequency converter P/N: HZ-50-3345. For longevity purposes, should the unit be turned off when not in use or left on?
A: To extend the service life, the frequency converter should be shut down when not in use and should be cleaned and maintained regularly. You can refer to the user manual instructions in the attachment.

2. 60Hz to 50Hz Frequency Converter Installation

Q: We have received HZ-50-3345 220V three-phase frequency converter with Wye (L1, L2, L3 + N, G) wiring, but I need help with the installation. I have found what looks to be a discrepancy between your User manual and the online user manual please see attached.

I need the following information:

1. Input amperage to the unit, protection breaker & wire size (US standard).
2. Output amperage, protection breaker & wire size (US standard).

A:

1. Input amperage (Max): 130A, we recommend that you use an input protection circuit breaker with a rated capacity of 250A and a copper cable Wire size of 35mm², which is equivalent to the American standard AWG2.
2. There is already a protective circuit breaker at the output end. You only need to select the appropriate cable according to the current of the load. The current capacity of the output terminal is related to the load capacity.

3. Wire Gauge and Ferrule Recommendations for 45kVA Frequency Converter

Q: Our system uses 8 gauge wire for 3-phase components in the HZ-50-3345 45 kVA frequency converter. What gauge of wire and ferrule type do you recommend to hook cables at the input and output of the 45kVA converter that you are shipping to Germany?
A: For this 3 phase converter, the input current is about 75A at full load and the maximum output current is 62A at 400V. Therefore, we recommend that the cable used at the input end should be able to withstand a maximum current of 100A, and the cable used at the output end can handle a maximum current of 60A.
Of course, the size of the cable used at the output is related to the load capacity. If the three-phase components in the system use 8-gauge copper wire (which can handle approximately 55A), the converter output can also use 8-gauge copper wire.

4. 3 phase Converter: Neutral Connection and Residual Current Breaker Installation

Q: See below, and the questions are related to our 3-phase converter "HZ-50-3303 & HZ-50-3310":

1. Is the N on the output internally connected to the ground, or is it insulated/floating? Should it be connected to the ground externally?
2. I have a residual current breaker upstream of the converter, but do I have to install a residual current breaker downstream from the converter as well?

A:

1. The output neutral N is connected from the internal transformer of the converter, and It is semi-floating. Therefore, the customer's load neutral line N can be directly connected to the N of our converter output terminal.
2. If you have a residual current breaker upstream of the converter, then No need to install a residual current breaker downstream from the converter.

5. How to Install a Frequency Converter?

Q: Our subject order was now on University and needs to be installed. Our Technical Engr. Mr Ronel needs the technical manual, installation, specs also the demo.
A: For the installation and use of a variable frequency power supply, please refer to the general user manual attached.

You only need to correctly connect the input voltage to the input terminals R, S, T, N, and G, then adjust the buttons on the panel to set the output voltage and frequency you want, and finally connect the output terminals U, V, and W to your load. Please also refer to the demo video below.

Related blog: How to Operate Cabinet Frequency Converter?

6. 50Hz to 60Hz Converter Electrical Requirements and Operational Advice

Q: This Model HZ-50-1103 frequency converter is sitting in my garage and my electrician is asking questions I was hoping you could answer:

The user manual I downloaded from your website indicates that the line/neutral input/output conductors need to be ≥4mm² which equates to 12 AWG. At 3kva and 230 volts input, the maximum current draw should be about 12.5 amps. I have a 20 amp grounded circuit that just powers electrical outlets that we plan to plug into so that should be sufficient for the load. However, my electrician is questioning the need for ≥4mm2 line/neutral input conductors since 2.5mm² conductors should be adequate to handle 22-23 amps. Further, the electrical outlet conductors throughout the property are nominally 2.5mm² which is adequate for a circuit protected by a 20 amp circuit breaker. If 4mm² line/neutral conductors are required, we’re not sure how this can be accommodated given the physical constraints of the home. Also, here in France, I’m so far not even able to source a male plug for the end of this cable that supports 4mm² conductors. Finding a plug that will handle 2.5mm² conductors and 16 amps is not a problem though.

Since we are converting 230V to 110V, I understand that the outlet line/neutral conductors may need to carry a higher current and I do have a 12-awg output cable that I can use to plug into a multi-socket surge protector. However, the equipment (solid state hi-fidelity sound electronic equipment some of which has small motors) I’m powering was hooked up to a 110V / 15 amp circuit when we lived in the United States which never tripped the breaker so I am very confident that I won’t be drawing more than that on the output side of this converter.

If for some reason we need to limit the input current on this device to less than 20 amps to accommodate 2.5mm² conductors, could we fuse the line or neutral input conductors for something less than 20 amps? Alternatively, can the over-current protection in the frequency converter itself be manually adjusted downward even if that means reducing the output power of the device? Lastly, my electrician is asking what the no-load power draw is for the frequency converter.

A: Yes, this model HZ-50-1103 frequency converter has an output current of 12.5A at 230V and a maximum output current of 25A at 110V. The output current of the single phase converter is related to the load capacity you connect. So if you are not using the converter at full capacity, you can use 2.5mm² copper cables instead of 4mm² cables, no problem.

9. Performance Verification Procedure for HZ-50-3375 Converter

Q: Is there a performance verification procedure you can provide me for the Hz-50-3375 frequency converter?
A: After you receive the converter, please follow the steps below for performance verification:

1.  Please check the appearance for obvious impact or damage.
2. Please read the instruction manual to understand the function of the power supply.
3. Please confirm whether the input voltage is consistent with the parameters of the purchased power supply. After confirming that it is correct, connect the input and output cables.
4. First, please turn off the output circuit breaker, turn on the power supply to the desired voltage and frequency, and run it for 1 to 2 minutes without load.
5. Please turn off the load, then turn on the power output circuit breaker, and then measure whether the output voltage and output frequency are consistent with a multimeter. After confirming that it is correct, the power supply can be operated with the load.

10. ATO Frequency Converter Setting

Q: I am setting up my ATO frequency converters (3 KVA benchtop, and 5KVA cabinet). Can you share some photos or videos or instructions on how and what's the best way to connect the terminals to the wall outlet? Also, how can I cover/insulate the open terminals on the frequency? Converter unit after connecting the cable wires to it?
A: For the operation and use of the converter, you can refer to our demo video below.

11. 50Hz to 60Hz Frequency Converter Installation and Wiring

Q: We are getting ready to install the HZ-50-3375 and HZ-50-33200 frequency converters out at the Mars Wrigley project. Do you have information on how to wire these or any pictures of a typical install? Are these typically fed with SO cord from the bottom opening? Any information can help.
A: Regarding the installation and wiring of frequency converters, the cables are usually connected from the bottom opening. R/S/T is the input power terminal, N is the natural wire, G is the ground wire, and U/V/W is the output three-phase voltage. You can refer to the attached user manual, as well as our operation demonstration video below.

Video 1: Cabinet frequency converter wiring and testing

Video 2: 3 phase frequency converter 50Hz/60Hz

Frequency Converter Troubleshooting

1. HZ-60-1101 Converter Troubleshooting: Fuse and Cap Replacement

Q: I have the converter HZ-60-1101. And it seems that is not working, I'm unable to dial or make any adjustments, I noticed that is missing one of the fuse 20A and the cap, can this be the cause and can I get this fuse/cap from a hardware store? Thank you for your time.
A: Yes, you can buy this 20A fuse/cap from a hardware store. Or you can carefully check whether the accessories that come with your converter include a spare fuse. If you find a spare fuse, you can replace it directly, and test again. If you still have problems, please send us a picture of the converter nameplate including a picture of the missing fuse for confirmation.

2. 50Hz to 60Hz Frequency Converter Troubleshooting

Q: I ran the HZ-50-3375 frequency converter, and this morning we saw this happen on the 75KVA FC unit.

• Fault 1: Display problem.
• Fault 2: Unit shutdown. Unknown reason.

I’ve given it a visual inspection and did not see anything out of the ordinary. Found that the unit was shutdown and found no one had tampered with it. I turned it on and it has the proper Voltage and Frequency as set. The current load is at 3.45 A. Please review the attached pictures and provide support ASAP.

A: For the 75KVA frequency converter unit.

• Fault 1: Display problem>>>Please try to start the converter without load. Can the voltage/frequency be displayed normally? If the display panel only displays all 0s, but the voltage of the output terminal is normal, it means that the display circuit board is faulty. Please confirm.
• Fault 2: The unit shuts down abnormally. Is there any sudden change in load during use or is the line connection abnormal? If the converter runs normally without load, you can connect the load again and monitor the specific circumstances of the failure during operation.

3. 75KVA Frequency Converter Troubleshooting: Capacitance Assessment

Q: We are having issues with our Hz-50-3375 frequency converter. It makes noise when we turn the output ON. Seems like issues with the U phase. Also, the U phase has had a lower voltage than the others.

• U-N = 82V
• V-N = 116V
• W-N = 117V

I tried to replace the motherboard with the extra motherboard I had. It resolved the voltage issue but still made noise. Please let us know when can you provide help.

A: We think that the noise may be due to an abnormality in the feedback capacitor. Please measure the U, V, and W three-phase feedback capacitance according to the attached troubleshooting document, check whether the capacitance is normal, and report the measurement result to us. It would be more helpful if a video could be provided to us for further confirmation. You can send us the large video file.

4. 3kVA Single Phase Converter Troubleshooting: Intermittent Beeping

Q: We have an HZ-50-1103 frequency converter in the USA that intermittently beeps and requires a reset when we turn on the equipment powered by it. Our equipment fires a contactor to draw the power and momentarily the equipment will draw a higher current.

In the UK we use CAT D motor-rated fuses to handle the initial surge. What surge can the HZ-50-1103 handle, or will there be another reason for it beeping and needing to be reset? Usually after resetting it operates perfectly until the next time it beeps and needs resetting.

A: We think that this situation should be that the driver board is abnormal, and we suggest that you replace it with a new driver board. Please provide your order number or send us the nameplate label of the converter to confirm if the unit is still under warranty. If it is within the warranty period, we can directly replace it for you free of charge; if it exceeds the warranty period, you need to pay.

Also, could you please tell us what the peak current your device draws at startup? The HZ-50-1103 can not handle inrush current, but you can adjust the potentiometer on the circuit board to increase the current protection threshold a bit. Please see the attached document, you can turn the potentiometer 8 turns counterclockwise and test again. We still need you to send the converter's nameplate label or order number to us for confirmation.

5. 60Hz to 50Hz Converter Troubleshooting and Expedited Replacement

Q: We currently own an ATO frequency converter model HZ-50-3310. We are having an issue with the unit not being able to obtain an output of 200V@400Hz while under the load of 200A.

It recently worked just fine but does not seem to meet the requirements now. We need from 195V to 210V @400Hz for our testing requirements. We have tried 2 known good units that we typically test with exactly similar results. One output leg (U) is good but the other 2 output legs (V&W) readings are reading 8-10 volts lower than leg “U”. We cannot maintain the 200V required for the test. I would also like a quote for a 2nd unit with the same specs shown on the data tag image attached. I need to get the present unit up & running ASAP.

Is there any way to expedite a repair/troubleshooting here on site of our present unit and expediting of a new unit we are interested in purchasing? Please advise your repair/troubleshooting and quickest purchase and ship on a new unit.

A:

1. First of all, the maximum output current of this 10KVA converter is only 27A. So the "200V@400Hz while under load of 200A." you mentioned below is the wrong number. It should be 20A, right?
2. Now, please remove the load connection, then run the converter with no load, use a multimeter to measure the phase voltages (U-N, V-N, W-N) of the output terminals, and feedback the measurement results to us. You can send photos of the multimeter's measurement readings to us for confirmation.
3. After completing step 2, you can measure the feedback capacitance of the V-phase and W-phase according to the attached troubleshooting document and feedback the measurement results to us.

6. 1KAV Single Phase Converter Troubleshooting: Tripping Breaker and Fuse Blowouts

Q: We ordered and installed one of your converters (Model: HZ-60-1101) for a client, and once we put a load on the converter, it blew a fuse. The equipment we are trying to supply is an Italian "insta-freezer" and it operates at 50Hz, 230V (line to neutral) and it draws 3.9 amps. We replaced the fuse after it blew initially, and now every time we turn on the output switch, it trips the breaker in the house electrical panel (it does not blow the fuse).

Note: The breaker trips even when there is nothing plugged into the output receptacle. FYI the converter is supplied with a dedicated 240V (2-pole) 15A circuit. (2-hots and no neutral). Would you please lend me some assistance in trying to resolve this matter?

A: The rated output current of the converter (model: HZ-60-1101) is 4.2A at 220VAC, and the quick freezer load is 230V/3.9A. This is an inductive load, and there is a surge current at startup. The converter should be overloaded and malfunctioning.

Now remove all loads and try running the converter with no load. Please check whether the converter can display normal operation without tripping and alarming. If there are still problems when running without load, the converter is damaged.

7. ATO 10kVA Converter Troubleshooting

Q: I have a couple of questions for you concerning the 10kVA unit we purchased from ATO.

1. When we slightly touch the phase switch but keep it at a fixed phase, either at U, V, or W that the current readings and hence, the power readings fluctuate by a few hundred mA and a few Watts. How can that problem be corrected?
2. I don’t understand what the information on the display is showing because the phase current shown and voltage shown when multiplied together should equal the Watts shown. For instance, 115V is shown and 11.41A is shown as well as 1205W is shown. So 115V*11.41A = 1312W. Can you help me understand how to read the data on the display?
3. What is the function of the black toggle switch next to the amber light beneath the input and output breakers on the front lower section of the unit? The user manual makes no mention of this. When I turn that switch ON, the amber light comes ON and the power consumption figures at the display increase. When I turn that switch OFF, the amber light turns OFF and power dissipation at the display decreases. I don’t understand what this is.

A: Thanks for the update, is the data you provided below tested with the connection load?

1. The power of the touch phase switch will change, which should be caused by a little fluctuation of the load when the machine is working. Because the output power is only regulated and frequency-stabilized, the power and current vary according to the load.
2. If you think the power display is inaccurate, it is recommended that you use a clamp ammeter to measure the actual output current to see if the actual current matches the displayed current.
3. This toggle switch adjusts the line voltage and phase voltage (with an indicator label next to it). When the amber light is on, the line voltage is displayed. If the amber light is turned off, the phase voltage is displayed. The line voltage must be higher than the phase voltage, for example, the phase voltage 115V*1.732 is equal to the line voltage 119.18V.

8. Diagnosing 5kW Frequency Converter Shutdown

Q: I'm trying to power an industrial oven with your 5kW model and the frequency converter keeps shutting down and beeping. I've checked the ground resistance and it's good, the ambient temperature is good also. Is there a way to tell if the unit is tripping on a short circuit as opposed to an overcurrent? I'm not able to get an amperage reading on the oven before the frequency converter shuts down. I've included the oven faceplate and the ATO model form for reference. Oven is 240V 1ph 50Hz 8A L-N.
A: We think this may be a short circuit. Because the oven is 240V 1ph 50Hz 8A, the load current is not large, so it should not be overloaded. So could you please test with another oven? Or test with another small load?

9. HZ-50-3330 Frequency Converter Troubleshooting

Q: I have some questions about frequency converter HZ-50-3330.

We have done some more measurements in Brazil. They see a current peak at a motor start, but nothing extreme. Sometimes this peak seems to cause the shutdown, but more often, the equipment continues to work as intended. Unfortunately, the device used to measure was averaging, so probably we got no reading of the highest peak value. We also saw a little dip (2-3 volts) in the input voltage when the output current increased. After a high current peak, they also saw an increase in the output voltage at the rear edge of the current peak.

1. Do you know the exact limits (low input voltage and high output current) for the alarm conditions for this converter (I sent the nameplate again)?
2. What are the overvoltage/undervoltage limits, and what are the current limits to shut down the output?
3. Is the shutdown immediate at e.g. an overcurrent in the output, or is there a time delay so that short current peaks are allowed (Like a slow fuse)?

A:

1. Regarding voltage protection: The converter has the function of limiting voltage or under voltage, and the protection comes from the main board. If the voltage is higher than the normal voltage or the specification of the input circuit breaker, the input circuit breaker will trip for protection.
2. Regarding current protection: The converter is shut down immediately without delay in case of output overcurrent. So your machine is 30kVA, and the rated current is 41.6A at 400V, as long as the motor start-up surge current is higher than 41.6A, the machine will trip for protection.
3. Please send the nameplate label of the load and motor to us for further confirmation.

10. Troubleshooting: Voltage Drop in 10KVA Frequency Converter

Q: I'm requesting technical assistance on the ATO.com 10KVA converter (S/N: HZ-50-1110) bought in 2017 and operating on-site since 2018. Today, we witnessed a failure where one phase voltage dropped off when measured against the neutral. Please advise/provide any troubleshooting procedure or possible root causes.
A: Please give us the following information so that we can better help you solve the problem:

1. Please send the converter nameplate label picture to us for further confirmation.
2. Regarding the When measured against the neutral you mentioned, how much does the phase voltage drop?

11. Resolution for Converter Usage and Functionality Issues

Q: I would like to solicit your opinion and concurrence on a couple of questions regarding the use and functionality of our 30kVa frequency converter. Since our unit is in three phases. We have decided to dedicate each leg/circuit of the three phases to three separate shops. This separation has worked fine but occasionally we would have separate incidents that would damage our capacitors. With the intent to correct this, we have installed inline fuses to prevent damage back to the capacitors. The first question is whether this method of wiring each phase separately is okay.  The second question is if our current use of the converter is okay, do you all have any recommendations or suggestions on what we can do to prevent future grounding/shorting/damage to the capacitors?

A:

1. Yes, this method requires separate wiring for each phase.
2. As long as you use the converter within the safe voltage/current range, no problem. Our frequency converter has short-circuit protection.

For the problem of occasional damage to the capacitor, pay attention to whether the capacitor has a withstand voltage or leakage of the shell, including whether the connected load is affected, etc.