Instructions for Field Retrofit of a Model 98A Digital Temperature Controller

Introduction

This document provides instructions for retrofitting a Model 98A Digital Temperature controller in place of an existing Model 85 Temperature controller. This instruction bulletin is divided into the following sections:

• 1- Safety Precautions
• 2- Parts included in retrofit kit
• 3- Removal of existing Model 85 controller
• 4- Transformer Center Panel modifications
• 5- Model 98A Digital Temperature Controller and Thermocouple installation
• 6- Completing the retrofit installation
• 7- Reference Drawings

While a great effort has been done to assure that this instruction bulletin is accurate and provides enough detail to assure a problem-free retrofit installation, all retrofit installations are different and therefore the finished installation may vary from the photographs shown.

Section 1 - Safety Precautions

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

• Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462.
• This equipment must only be installed and serviced by qualified electrical personnel.
• Turn off power before installing, removing, or working on this equipment.
• Always use a properly rated voltage sensing device to confirm power is off.
• Ensure all personnel, tools, controller wiring, and other work material or equipment are cleared from the transformer and the control box before turning ON power to the controller.
• Before applying power, make sure that all personnel and equipment are clear of the blowers or fans.
• Replace all devices, doors, and covers before turning on power to this equipment.

Failure to follow these instructions will result in death or serious injury.

Read and understand this entire instruction bulletin as well as the instruction bulletin for the Model 98A Digital Temperature Controller for Medium Voltage Transformers and the instruction bulletin that was provided with the transformer before installing, operating or maintaining this equipment. (Refer to instruction bulletin #43500-054-34.)

Disconnect power and verify that the transformer is de-energized before installing this equipment. Do not rely on visual indications such as switch position or fuse removal for determining a de-energized condition. Always assume that a terminal is energized unless it has been checked with a properly rated meter to ensure that the terminal is de-energized and grounded.

Section 2 - Parts Included in Retrofit Kit

The following parts are included in this retrofit kit. Please verify that you have all of the parts before beginning the retrofit procedure. If you are missing any of these items please contact a Schneider Electric Services at 1-888-778-2733.

• Qty-1 Model 98A Digital Temperature Controller pre-mounted and wired to mounting panel.
• Model 98A Digital Temperature Controller Fuses: Qty-1 1 amp MDA-1, Qty-1 20 amp MDA-20
• Hardware Package including: Qty-6 3/8-16 x 1-1/4" Bolts, Qty-6 3/8-16 Nuts, Qty-6 3/8 Split Ring Lock Washers, Qty-12 3/8 Flat Washers, 2 Doz. Wire Tie's, Qty-4 14-20 x 1" Bolts, Qty-4 14-20 Nuts, Qty-4 14-20 Nuts, Qty-8 1½ Flat Washers, Qty-4 Wire Clamps
• Qty-1 Glass Polyester Thermocouple Support Rod.
• Qty-60ft Thermocouple Wire.
• Qty-1 Model 98A Digital Temperature Controller Danger Label, p/n 43500-169-09
• Qty-6 Fan/Blower Danger Label, p/n 43500-169-02
• Model 98A Digital Temperature Controller Instruction Bulletin, p/n 43500-054-34

Section 3 - Removal of Existing Model 85 Controller

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

• Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462.
• This equipment must only be installed and serviced by qualified electrical personnel.
• Turn off power before installing, removing, or working on this equipment.
• Always use a properly rated voltage sensing device to confirm power is off.

Failure to follow these instructions will result in death or serious injury.

Remove the transformer enclosure front panels to gain access to the interior of the transformer. Note: The front and rear center panels of the transformer are not removable.

Remove the existing thermistor wiring from the transformer coils and cut all wire tie supports.

Disconnect all wiring from the rear on the Model 85 Controller (See Figure 1). Note the locations of the wires and the wire numbers. The new Model 98A Digital Temperature Controller wires will connect to these terminals.

On units with a Fan Control Panel, disconnect all of the wiring coming from the Model 85 Controller connected to the panel. Note the locations of the wires that you are removing. The new Model 98A Digital Temperature Controller will connect to the same terminals.

Remove the Model 85 Controller from its chassis and unbolt the chassis from the center panel. Remove any remaining wiring and thermistor wire supports.

Figure 1: Typical Model 85 Controller wiring. (Image shows wiring connections for the Model 85 controller, including thermistor wire and fan control panel connections.)

Section 4 - Transformer Center Panel Modifications

CAUTION

PANEL MODIFICATION HAZARD

Before cutting the center panel verify that there are no wires, cables or other obstructions within the new cutout area.

Failure to follow these instructions will result in equipment damage.

Remove any exterior unit nameplates that are within the cutout or mounting panel area and save for later reinstallation. Refer to drawing 24806-007-01 located in Section 7 of this bulletin for the cutout size and mounting hole locations.

Before cutting the new opening be sure that there is adequate room for the new mounting panel to mount flush with the transformer center panel. Adjust the cutout location as necessary.

Take all necessary precautions to assure that no metal fillings fall into the transformer coils. Smooth any rough edges of the cutout before installing the new controller.

Figure 2: Typical Existing Model 85 Controller Installation. (Image shows the existing Model 85 controller installation with labels indicating the new cutout for the Model 98A Controller Assembly and the Fan Control Panel.)

Section 5 - Model 98A Digital Temperature Controller and Thermocouple Installation

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

• Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462.
• This equipment must only be installed and serviced by qualified electrical personnel.
• Turn off power before installing, removing, or working on this equipment.
• Always use a properly rated voltage sensing device to confirm power is off.
• Assure proper electrical clearance of a minimum of 6 inches through air for medium voltage coils and leads and a minimum of 1 inch through air for low voltage coils and leads.
• Assure the sensor tubes and the thermocouples are installed in the low voltage coils only.
• Replace all devices, doors, and covers before turning on power to this equipment.

Failure to follow these instructions will result in death or serious injury.

After cutting the opening (refer to drawing 24806-007-01) in the transformer center panel, mount the new Model 98A Digital Temperature Controller using the provided 3/8" hardware. On outdoor installations, seal the edges of the new controller panel with clear silicone.

On units with a Fan Control Panel, route the pig-tailed wires from the bottom of the Model 98A Controller into the panel through the hole previously used by the old controller. (Refer to drawing 24806-001-5X)

On units without the Fan Control Panel, connect the wires from the new Model 98A Controller to the existing terminals that the old Model 85 Controller were connected.

Refer to wiring diagram 24806-004-001 located in Section 7 along with the previous controller wiring diagram that was furnished with the transformer for the wiring connections.

Install the new thermocouple support rod to the top core clamp as shown in figure 3 using the 3/8" hardware provided. The support rod does not have to be centered. If the rod is too long it can be trimmed.

Figure 3: Controller Installation and Typical Thermocouple Wire Routing. (Image shows the new thermocouple support rod, thermocouple wires routed into the Model 98A Controller, and the new Model 98A Controller mounted to the center panel.)

Next make the three thermocouples. Begin by cutting approximately 20ft (6m) from the coiled thermocouple wire that is provided in the kit. Strip 1.0" (25mm) from one end of the thermocouple wire. (Note: There is an outer covering of insulation and each of the bimetal wires is also insulated. This insulation must be removed as well). After completely stripping the wires, twist the ends together tightly (see Figure 4C). Repeat for each thermocouple. Do not solder the connection.

Starting on one phase of the transformer insert the stripped end of the thermocouple wire into the insulating tube or thermowell hole until it stops (approx. 4" (100mm) for the tube and 2"(50mm) for the hole) (see Figure 4A and 4B).

Route the wire up to the transformer top core clamp and toward the thermocouple support rod. The thermocouple wire must be firmly supported to assure proper electrical clearance of a minimum of 6 inches through air for medium voltage coils and leads and a minimum of 1 inch through air for low voltage coils and leads. To keep the wires secure route or weave them through any available holes in the core clamp flange or gussets. The wire should not be coiled or allowed to sag. Route the wire under the thermocouple support rod and through the first hole closest to the transformer clamp. The wire is then routed along the top of the rod and then down through the second hole at the end of the rod and finally into the right side of the Model 98A Controller (see Figure 3). Fasten the wire to the thermocouple support rod with wire ties.

Once all three thermocouple wires have been run into the Model 98A Controller connect the thermocouple wires to the controller as shown in Figure 5. Leave enough slack in the wires to allow full opening of the Model 98A Controller. Support the wires using the provided thermocouple clamp. See the wiring diagram 24806-004-01 in Section 7 of this bulletin for the wiring connections.

After completing the thermocouple wire connections seal the thermowell holes in the coils with clear silicone.

Figure 4A: Sensor Well. (Image shows a temperature sensor tube well located in the LV coils, typical for all LV coils, adjacent to the HV connections of the transformer (Dry type coil).)

Figure 4B: Thermowell Hole. (Image shows a temperature sensor tube well located in the LV coil, typical for all LV coils, adjacent to the HV connections of the transformer (Cast type coil).)

Figure 4C: Completed Thermocouple. (Image shows a completed thermocouple connection.)

Figure 5: Thermocouple Connections. (Image shows the thermocouple connections on the Model 98A Digital Temperature Controller.)

Section 6 - Completing the Retrofit Installation

Apply the Model 98A Controller Danger label, p/n 43500-169-09 next to the Model 98A Controller. The label can be applied above or below or to the right or left of the controller (see Figure 6).

Apply the Fan/Blower Danger label, p/n 43500-169-02, to the bottom core clamp near the fans or blowers. Apply three labels on the front and the remaining three labels to the back (see Figure 7).

FUSING:

Two fuses are provided for the Model 98A Controller, a 1 amp and a 20 amp. If the Model 98A Controller is wired to the Fan Control Panel then install the 1 amp fuse in the rear of the Model 98A Controller in the 'F2' fuse location. If the Model 98A Controller is directly controlling the fans/blowers, install the 20 amp fuse in the 'F2' fuse location.

NOTE: This 20 amp fuse may not provide adequate protection for smaller loads. If a smaller fuse is required, it is the installer's responsibility to correctly size the smaller fuse based on all applicable National Electrical Code rules and the fan/blower power requirements.

Refer to the Model 98A Digital Temperature Controller Instruction Bulletin for Power Logic Monitoring connections and MODBUS protocols.

Before energizing the Model 98A Controller for the first time, please review the controller operation procedure in the Model 98A Digital Temperature Controller Instruction Bulletin, p/n 43500-054-34. Also refer to the transformer instruction manual that came with the transformer for any startup testing that is required before re-energizing the transformer.

Figure 6: Model 98A Controller Label Installation. (Image shows the placement of the Model 98A Controller Danger Label.)

Figure 7: Fan/Blower Label Installation. (Image shows the placement of the Fan/Blower Danger Label on the bottom core clamp.)

DANGER

HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH

• Apply appropriate personal protective equipment (PPE) and follow safe electrical work practices. See NFPA 70E or CSA Z462.
• This equipment must only be installed and serviced by qualified electrical personnel.
• Turn off power before installing, removing, or working on this equipment.
• Always use a properly rated voltage sensing device to confirm power is off.
• Ensure all personnel, tools, controller wiring, and other work material or equipment are cleared from the transformer and the control box before turning ON power to the controller.
• Before applying power, make sure that all personnel and equipment are clear of the blowers or fans.
• Replace all devices, doors, and covers before turning on power to this equipment.

Failure to follow these instructions will result in death or serious injury.

Section 7 - Reference Drawings

This section contains reference drawings for the retrofit installation, including:

• Controller wiring pigtails and exit fitting details.
• Panel cutout details and dimensions.
• Wiring diagrams for both the Model 98A and Model 85 controllers.

Notes on Drawings:

• Engineering drawings are proprietary to Schneider Electric.
• Dimensions are in inches unless otherwise specified.
• Refer to specific drawing numbers for detailed information (e.g., 24806-001-5X, 24806-004-01, 24806-005-01, 24806-007-01).