GCK Low Voltage Switchgear

Operating conditions

1. Ambient air temperature: -5℃ ~+40℃ .
Daily average temperature: ≤35℃ .
When the actual temperature exceed the range, it should be used by reducing the
capacity accordingly.
2. Transport and store temperature: -25℃ ~+55℃. do not exceed +70℃ in short
time.
3. Altitude: ≤m.
4. Relative humidity : ≤50%, when temperature is +40℃ .
When temperature is low, larger relative humidity is allowed. when it is +20℃,
relative humidity can be 90%. Since the temperature change will make out
condensation.
5. Installation inclination: ≤5%
6. Applicable in the places without corrosive and flammable gas.
Note: Customized products are available.

Goto Beike to know more.

Technical data

1. Electric datas
1) Rated insulation voltage: 690V/V
2) Rated operational voltage: 400V/690V
3) Rated frequency: 50/60Hz
4) Rated impulse withstands voltage: 8kV
5) Rated voltage of auxiliary circuit: AC380/220V, DC110/220V
6) Over-voltage grade: III
7) Rated current: ≤A
8) Rated current of horizontal bus bar: ≤A
9) Rated current of vertical bus bar: A
2. Mechanical items
1) Incoming and outgoing mode
2) Cable incoming and outgoing
3) Connection mode
4) The functional units completely separated or partially separate

Feature

GCK panel is combination structure with bolt. The complete panel is compose of door, terminal board , baffle plate ,supporting frame and drawer, busbar, etc.
Basic frame adopts FA28 type or KB type (Ctype) to combine with together. Total structural components of frame are connected by self-tapping screw.
It should add to door, face place, baffle plate, supporting frame and drawer to finish completed panel by requirements.
The installation hole of body and components modules E=25mm change,flexible and convenient to install.
Drawer unit height divide into ½ unit, 200mm, 300mm, 400mm, 500mm, and 600mmm series. The loop current decide the drawer height,virtual installation height is mm.
GCK panel withdrawable function unit adopts special push (pull) mechanism, light
structure, perfect interchange. It indicate of working position, test position and
isolating position mechanical locking condition. Install additional pad lock for operating handle.
The frame and inner metal components are galvanized to assure reliable earthing .
GCK basic frame is combination assembly type structure, adopt standardized module design. for combination assembly type structure, the standard module design.
Compact structure, flexible assembly, can be assembled into a protection, measurement and control, indicating etc. standard unit, Can choose assembly according to requirement, To form different frame Features and drawer unit.
1. The cabinet frame
C type material adopted for the mainframe, Frame parts and Special parts will be provided by our company to make sure the accuracy and quality.
● Parts forming size, hole size,Equipment interval adopt modularization. (E=25mm)
● The internal structure should be galvanized.
● The top cover is detachable,horizontal bus can be installed easily after removing the top cover, Hand ring
● External phosphating treatment; Then use electrostatic epoxy powder coating.
● Cabinet frame is divided into the busbar compartment, functional compartment, the cable compartment three separate interval, Can prevent accidents diffusion and convenient charged repair.
2. Functional unit (Withdrawable part)
● Functional unit: Feeder unit , Motor unit,utility power unit.
● The high modulus of drawer unit is 200mm, include 1/2unit,1unit,2 unit,3 unit four size series.
Unit loop rated current below 630A.
● Each MCC Cabinet can install 9 set drawer with 1 unit , or 18 set drawer with ½ unit .

For more GCK low voltage switchgear short circuit ratinginformation, please contact us. We will provide professional answers.

● The compartment door plate is interlocked between operating mechanism and drawer, the door can be open until the main switch is on the close position
● The main switch operating mechanism can be locked in close or open position by a padlock , the equipment can be maintained safely.
● There are main circuit outlet plug,auxiliary circuit secondary plug and earthing plug at the back of function unit.
● The earthing plug make sure the protection circuit continuity when drawer on Separation tests connection position.
● Functional unit compartment by metal partition board.
● Compartment valve, can be open and close automatically, with drawers pushed and pulled so that in the compartment without touching the vertical busbar.
3. Busbar system
● Vertical bus uses polycarbonate engineering plastic shell sealed
● GCK, GCL busbar system use 3P4W, 3P5W, Horizontal busbar will be installed at the top of cabinet, N phase, PE phase. Can be installed on the top of the cabinet, and can also be arranged in the cabinet bottom.

Overall and mounting dimensions(mm)

The effective height of installation
1. Electric cabinet and buscouple cabinet
Cabinet width can be 600,800,,,(800-400)mm according to rated current and method of incoming and outgoing.
Depth of cabinet is 800,(Advise to use mm ,The top incoming and top outgoing must be mm)
2. Feeder cabinet
Cabinet Width: 600, 800mm
Cabinet depth: 600, (advise to use mm top outgoing cabinet must be mm)
3. Motor control cabinet
Width: 600, 600+200mm
Depth of cabinet: 800, mm(advise to use mm top outgoing cabinet must be mm)
Power compensation cabinet
Width: 600(4, 6 loop), 800(8), (10 loop )mm
cabinet depth: 800, mm

For more information, please visit GCK modular low voltage switchgear.

Hi All,

I'm working with a 480/277V A switchgear which has no labels on the cover or the breakers on the AIC rating. I'm adding a stepdown 112.5kVA transformer and a 400A panel downstream for EV chargers. The building department wants me to show the available fault current and the short circuit rating at each piece of equipment.

Please bear with me as this is a first for me

1) If I cannot find the AIC rating, does this mean I have to do a full short circuit study, going all the way upstream and contacting the utility to find out what their transformer's AFC/impedances are?
2) If I did have the AIC rating, would all I need to show to the building department be the available fault current at the secondary of my new transformer and panel, and the appropriate breaker SSCR ratings to show I'm covering the maximum available fault current? You need to prove any additions made to the 480V existing equipment have the appropriate AIC, so you need to know the available fault current or a worst case.

If all you need is to determine a minimum AIC/SCCR for devices and equipment after the transformer, you can determine a worst case fault by assuming an infinite source. Simply take the full load amps of the transformer and divide by its per cent impedance (%Z). Thanks Jim.

So to check my calcs, I would get 112.5kVA/208*sqrt(3) = 312.27 A (FLA) and then my AFC = 312.27A/.05 (assumption for now) which would land me at 6.25kA.

Making my breaker protecting the transformer a 10KAIC breaker. I'm assuming everything downstream of that is safe to size to the same KAIC value? My panel MCB and branch breakers also at 10KAIC?

When would I need to do a full short circuit study? Is that if this transformer was existing and I was planning on using it to add a panel?

Thanks Jim.

So to check my calcs, I would get 112.5kVA/208*sqrt(3) = 312.27 A (FLA) and then my AFC = 312.27A/.05 (assumption for now) which would land me at 6.25kA.

Making my breaker protecting the transformer a 10KAIC breaker. I'm assuming everything downstream of that is safe to size to the same KAIC value? My panel MCB and branch breakers also at 10KAIC?

When would I need to do a full short circuit study? Is that if this transformer was existing and I was planning on using it to add a panel?

When you say "breaker protecting the transformer" is that on the primary or secondary side? If on the primary side, the AFC that sees would be based on the upstream transformer and conductor length.

Thanks Jim.

So to check my calcs, I would get 112.5kVA/208*sqrt(3) = 312.27 A (FLA) and then my AFC = 312.27A/.05 (assumption for now) which would land me at 6.25kA.

Making my breaker protecting the transformer a 10KAIC breaker. I'm assuming everything downstream of that is safe to size to the same KAIC value? My panel MCB and branch breakers also at 10KAIC?

When would I need to do a full short circuit study? Is that if this transformer was existing and I was planning on using it to add a panel?

Yes, your example is correct. Just be aware that transformers less than 500kVA often have impedances <5%.

Short circuit current does not get worse at downstream equipment unless there is another downstream source.

You should do a full short circuit study when the infinite bus method results are not satisfactory or when performing Arc Flash analyses.

When you say "breaker protecting the transformer" is that on the primary or secondary side? If on the primary side, the AFC that sees would be based on the upstream transformer and conductor length.

Yeah, I meant on the primary side. Okay, so my calculation since my secondary voltage is 208V is for the AFC on the transformer secondary and so my panel main and branch circuits would be rated for 10kAIC. On the primary side, it looks like I'll have some digging to do and contact the utility because there's absolutely no information on the switch gear regarding the kAIC rating. Is that right?

Yes, your example is correct. Just be aware that transformers less than 500kVA often have impedances <5%.

Short circuit current does not get worse at downstream equipment unless there is another downstream source.

You should do a full short circuit study when the infinite bus method results are not satisfactory or when performing Arc Flash analyses.

Thank you. I just responded to the other comment regarding the primary vs secondary side of the transformer but now come to think of it...knowing what the utility transformer's impedance/voltage is is probably unnecessary because the voltage would be so much higher. So the worst case would indeed be the the secondary of my new transformer? Sorry for all the questions guys, but appreciate all the responses!

. So the worst case would indeed be the the secondary of my new transformer? Sorry for all the questions guys, but appreciate all the responses!

No the AFC on the primary of your new transformer would be much higher. You will need to either get a figure from the utility or get the utility transformer information and calculate it yourself.

Thank you. I just responded to the other comment regarding the primary vs secondary side of the transformer but now come to think of it...knowing what the utility transformer's impedance/voltage is is probably unnecessary because the voltage would be so much higher. So the worst case would indeed be the the secondary of my new transformer? Sorry for all the questions guys, but appreciate all the responses!

Protective device AIC selection needs to be done separately for each side of the transformer.

Are you adding a new 480V protective device that will be feeding this new transformer? If you are you need to determine what AIC is needed based on the calculated fault current.

If you are using an existing protective device, how sure are you that its AIC was determined correctly? For example has the utility changed its transformer since the original service installation?

No the AFC on the primary of your new transformer would be much higher. You will need to either get a figure from the utility or get the utility transformer information and calculate it yourself.

Okay, I think I am getting closer. My new breaker serving my 112.5kVA transformer on the switchgear is going to see a much higher AFC because despite my higher operating voltage, the upstream transformer is going to be significantly larger. If for example's sake the A main on the switchgear was sized exactly for 125% of the kVA rating of the utility transformer, I may have something like a 1.3 MW utility transformer upstream, giving me roughly A FLA and at 5% impedance and roughly 32kA available fault current worst case scenario. I won't actually assume my OCP on the switchgear to obtain my utility transformer's kVA value when actually calculating.

Am I there yet or am I still missing something?

Definitely anecdotal but just to give you a ballpark number, the SCA on a couple of 112.5 kva I installed turned out to be in the 15-20k range.

Thanks. I'm doing work in a commercial space with relatively low demands but they definitely juiced the power coming into the building. Maybe an uncommon situation, but if the utility transformer is as large as I'm expecting, looks like the SCA might be a good amount higher than that.

Thanks. I'm doing work in a commercial space with relatively low demands but they definitely juiced the power coming into the building. Maybe an uncommon situation, but if the utility transformer is as large as I'm expecting, looks like the SCA might be a good amount higher than that.

I was referencing the secondary side of the transformer only not your 480 panel.

Thanks. I'm doing work in a commercial space with relatively low demands but they definitely juiced the power coming into the building. Maybe an uncommon situation, but if the utility transformer is as large as I'm expecting, looks like the SCA might be a good amount higher than that.

Be careful.
Utilities undersize their transformers as much as 50% versus what an NEC calculated load is. And because they have to pay for transformer losses they often buy units with low %Z.

But, then the utility says it never knows when a transformer might be replaced with a larger unit, so they give you available fault currents based on some possible future condition. For example during a disaster recovery they may install an oversized transformer if it is available and fits on their pad.

Definitely anecdotal but just to give you a ballpark number, the SCA on a couple of 112.5 kva I installed turned out to be in the 15-20k range.

True. My notes tell me %Z = 1.7% for a 112.5 kVA transformer (banked 3 X 37.5 kVA, SCA= 18 kA)