JDZ9 35kV Voltage Transformer for 27.5kV and 35kV

Description

JDZ9-35 at a Glance

The JDZ9 35kV voltage transformer is a single-phase, epoxy-resin cast unit with a fully enclosed pillar body, built for indoor installation in 35 kV switchgear. It provides the voltage signal for metering and relay protection at 50 Hz or 60 Hz, and it mounts directly inside KYN-35 type cubicles and comparable high-voltage boards.

The JDZ9 35kV voltage transformer series covers three builds: the JDZ9-35 for standard 35 kV duty, the JDZF9-35 with two separate secondary windings, and the JDZ7-27.5 for 27.5 kV electrified railway traction supply. All three share the same cast body and the same 1,000 VA limit output.

Reading the Type Designation

The letter F is the one that changes the wiring, not the price tier. A JDZF9-35 gives you two independent secondary circuits from one primary winding, which is what allows a metering signal and a protection signal to come from the same unit without sharing a core.

Ratings, Accuracy and Output

Every figure below is a matched pair: the rated output is valid at the accuracy class printed beside it, and at no other combination.

Ratios or combinations outside this table are built to order after review, not selected from a list. If your scheme needs a non-standard secondary voltage or a different class pairing, send the requirement and it will be confirmed rather than approximated.

Accuracy Class and Rated Output Are a Pair, Not a Menu

The single most common specification error on this unit is asking for the highest accuracy class at the largest output. The two figures are tied together by the winding design.

On the JDZ9 35kV voltage transformer, 0.2 class is available at 30 VA, 0.5 class at 80 VA, and 1.0 class at 120 VA. You cannot order 0.2 class at 120 VA, because the core and winding that hold 0.2 over the specified range cannot also deliver four times that burden. A quotation offering both is either misread or wrong.

What to send instead: state the total burden of the connected meters, transducers and relays, including the lead resistance, and the accuracy class your metering scheme requires. If the burden exceeds what the class allows, the answer is a larger unit or a second core, not a bigger number on the same core.

What the 1,000 VA Limit Output Means

The limit output is not a rated figure and should not be used for selection. It states the thermal ceiling of the secondary winding: the burden the unit can carry briefly without damaging the insulation, before the winding overheats.

It matters in two situations. During a fault the secondary voltage can rise and the connected burden draws more current than at rated voltage, and the limit output tells you how much of that the unit survives. It also matters when a buyer tries to run several relays from one core: 1,000 VA looks generous, but the accuracy class is only valid up to 80 VA on the JDZ9-35, so the usable range is far below the thermal ceiling.

Railway Traction: 27.5 kV and 35 kV

The JDZ7-27.5 in this series is built for 27.5 kV electrified railway traction supply, and it is the version specified for traction substations and sectioning posts rather than for distribution networks.

Traction duty differs from distribution duty in two ways that affect a voltage transformer. The supply is single-phase and the load is highly variable, with harmonics from the traction converters present on the busbar. The measurement is also tied to billing between the railway operator and the supply authority, which pushes the accuracy requirement toward 0.2 class at a higher burden than a distribution feeder would need.

That is why the 27.5 kV build is listed at 50 VA for 0.2 class and 100 VA for 0.5 class, above the 30 VA and 80 VA of the 35 kV build, while carrying the same 31.5/95/185 kV insulation level appropriate to the traction system. If your project is a 35 kV traction feeder rather than 27.5 kV, state the system voltage and the metering scheme: the two traction voltages use different builds and the choice is not interchangeable.

Installation in KYN-35 and Similar Cubicles

The JDZ9 35kV voltage transformer mounts inside an indoor metal-clad cubicle, with the primary connected to the busbar or the line side and the secondary run to the metering or relay compartment. KYN-35 switchgear is the reference application, and the mounting dimensions below are set to suit that cubicle family.

Because the body is fully cast, it accepts installation in any direction. That is what lets the same unit fit a vertical busbar compartment and a horizontal metering chamber without a bracket redesign, and it is worth confirming against your cubicle drawing before the order rather than after.

Terminal Box and Tamper-Resistant Metering

The secondary terminals sit in a sealed box with three possible exit directions, so the wiring can leave toward the relay panel, downward into a duct, or sideways into an adjacent compartment without re-routing.

On revenue metering points the box also carries anti-tamper provision, which matters where the metering is accessible to the consumer. For utility billing installations, state that the application is revenue metering at the inquiry stage: it affects how the terminal box is sealed and how the nameplate is marked.

Tropical and Polluted Sites

The fully enclosed cast body of the JDZ9 35kV voltage transformer is resistant to dirt and moisture and is suitable for tropical areas, where humidity and surface contamination would degrade an open construction faster. Maintenance is limited to removing surface dirt on a regular schedule; there is no oil level, no gas pressure and no desiccant to replace.

Where the site has salt fog or heavy conductive dust, state the pollution level with the inquiry. The creepage distance is set in the casting, so a unit built for a clean indoor switchroom cannot be upgraded later for a coastal or cement-plant environment.

Outline Dimensions and Mounting

The body is 395 mm wide and 510 ± 5 mm high, on a base plate of 550 ± 2 mm by 280 ± 1 mm. Mounting hole centres are 500 ± 1 mm and 425 ± 1 mm, with the fixing holes at M12 clearance. The secondary terminal box sits at one end of the base.

When a Different PT Fits Better

• Semi-insulated construction for the same 35 kV class. The JDZX9-35 voltage transformer uses the semi-insulated variant, which suits systems where one primary end is at ground potential.
• 10 kV and below. The JDZ10 cast voltage transformer covers 3 kV, 6 kV and 10 kV in the same indoor family.
• Outdoor installation. This is an indoor unit. An outdoor structure needs a different frame.

The full range is listed under voltage transformers, and the accuracy and burden relationship is explained in our guide to voltage transformer accuracy and instrument PT selection.

Standards and Routine Tests

Units are built and tested to the instrument transformer standards for this class. Routine tests on every unit cover power-frequency withstand, insulation resistance, ratio and polarity, and ratio error and phase displacement at the rated output stated for its accuracy class.

The 40.5/95/185 kV insulation level is verified as part of the routine and type testing programme. Type test reports for temperature rise and impulse withstand are available for project documentation.

Manufacturer Supply, OEM and Wholesale

The JDZ9 35kV voltage transformer series is manufactured and supplied direct. For traction projects the usual pattern is a project supply matched to the substation bill of materials, with drawings and test reports issued for approval. For switchgear builders, units are supplied against a frozen ratio and class specification under OEM or private-label marking. Distributors order against a standing specification for repeat supply.

Non-standard ratios and the dual-winding JF build are quotable because the winding is made to order rather than pulled from stock.

Price, MOQ and Lead Time

• MOQ. Single units for standard ratios. Custom ratios and private-label marking carry a higher minimum.
• Price drivers. Voltage class, accuracy class, rated output, single or dual winding, and quantity. A 0.2 class unit sits above a 1.0 class at the same ratio.
• Lead time. Confirmed against the production schedule. Traction builds and non-standard ratios take longer than standard distribution units.
• Payment. Deposit with balance against the bill of lading copy; letter of credit for project quantities.

What to Send With Your Inquiry

• System voltage: 27.5 kV traction or 35 kV distribution
• Voltage ratio, primary and secondary
• Accuracy class and the total burden of connected devices
• Single winding (JDZ9) or dual winding (JDZF9)
• Rated frequency, 50 Hz or 60 Hz
• Cubicle type and mounting orientation
• Pollution level and site altitude
• Quantity, destination port and required delivery date

Send those through the quote form on this page. The accuracy class and burden pair is the item that most often needs a second round, so including both shortens the quotation.

FAQ

Request Quote