Emerson CVS Hardwired Constant Voltage Transformers Operating and Service Manual

Emerson Power Protection and Conditioning Operating and Service Manual - CVS Hardwired Constant Voltage Transformers.
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Introduction
This operating and service manual has been prepared to ensure that your 

Sola/Hevi-Duty Constant Voltage Transformer can 

be operated and serviced with minimal effort and 

involvement. This manual covers Sola/Hevi-Duty 

Constant Voltage Sinusoidal (CVS) Transformers.

Installation - Mechanical Position
All stock sizes with end housings are intended to be 

mounted with the silk-screened this side up legend 

facing upwards. This will place the ventilated capacitor 

compartment downward, thus providing cooler 

operation of the capacitor(s). However, all units will 

give satisfactory performance if mounted in a horizontal 

position. In either case, the unit should be mounted in 

an area where it is unlikely that anyone will come into 

contact with the core surface of the unit.

Mounting Considerations
If a unit is to be wall mounted, the mounting hardware should be sized as in 

Table 1 below. All mounting holes provided must be used.

Table 1: Mounting Screw/Bolt Sizing

Figure 1:  Mounting Holes and Dimensions

Installation – Electrical
On 60VA or smaller units, screw-type lugs in the outlet box are marked “input” 

and “output”, and no connection diagram is necessary. Units rated 120 to 

15000 VA are provided with multiple inputs for any one, two, three, or four 

different line voltages, and some have provision for three-wire output.  With 

all units, a connection diagram is attached to the inside lid of the box cover, or 

inserted in the outlet box. Figure 2 shows typical connections for –8 models, 

and Figure 3 shows multiple input connections for all other models.  Figure 4 

shows the output connections for all models.

Figure 2: Electrical Connections for -8 models

Input & Output Connections – All except 250 VA

Input Connections - 250 VA Only

*Note:  The entire load up to the rated capacity of the unit can be drawn from either half of

             the 240 volt winding.  It is not necessary to divide or balance the load.

Table 3: Recommended  Wire Sizes and Fusing

* Leads in the wiring department must be sleeved with 105 oC sleeving. 

Figure 4.  Three Phase Connections

A: Isolated, Single Phase Loads

B: Separate, Single Phase Loads in Grounded Wye

Multiple Operation
Two CVS transformers with the same rating may be connected with their 

inputs and outputs in parallel. The regulating action will usually be excellent 

although the standard ±1% cannot be guaranteed. Series connection of either 

input or output is not recommended.

Use With Rectifier Loads
The ratio of crest to rms values is approximately 1.3 at rated load, and slightly 

lower at fractional loads. This factor must be considered when all or a portion 

of the voltage is rectified. The rectified voltage will now be 10 – 15% lower 

than if connected directly to a sinewave source.

Operation With Motor Loads
Because of the current limiting effect described later, special attention should 

be given to motor applications. In general, the CVS must have a load rating 

nearly equal to the maximum power drawn during the starting cycle. This may 

run from two to eight times the normal running rating of the motor. In doubtful 

cases, it is advisable to measure the actual starting current.

Cascade Operation
For applications requiring close regulation, two CVS transformers may 

be operated in “cascade”. The output of the combination will show little or 

no detectable change arising from supply line variations of up to ±15%.  

However, the combined units will still be frequency sensitive (as discussed 

under Effect of Frequency, page 15). Since even good power systems may 

vary in frequency by 0.1% or more, the output of a Sola/Hevi-Duty cascade 

combination may vary by up to 0.25% from this cause alone. In actual 

practice, then, a cascade combination is highly recommended for special 

applications requiring regulation in the general region of ±0.25%.  If the 

tandem setup is to be operated at near full rating, then the Type CVS “driver” 

unit should be one standard size larger than the driven unit, in order to 

overcome the losses in the latter.

Outline A

Outline B

Outline C

All Except 250 VA

250 VA only

Constant Voltage Sinusoidal Transformers

Operating and Service Manual

Figure 3: Electrical Connections for Non-8 models

Note:  Secondaries are not grounded.  Ground X2 per Code.

Rated VA of Regulator

Min. Diameter of Steel Mounting Screw

30-120

#10 Machine Screws

250

1/4” bolts

500 to 1000

5/16” bolts

1500 to 10000

3/8” bolts

15000

1/2” bolts

All ratings depend on natural draft air circulation for cooling. They should not 

be mounted in confined or enclosed spaces unless special provisions have 

been made for ventilation. Technical Services is available for assistance in 

doubtful situations (see note on Operating Temperature). Table 2 and Figure 1 

show model number with their weight and physical dimensions.

Table 2:  CVS Weights and Physical Dimensions, 60 Hz Single Phase

VA

Catalog

Number

Outline

Drawing

Dimensions

Approx.

Shipping

Weight (lbs)

(in)

B

(in)

C

(in)

D

(in)

E

(in)

F

(in)

G

(in)

H

(in)

30

23-13-030-2

A

6.12

5.19

3.47

4.00

3.50

3.00

1.75

.22 x .59

7

60

23-13-060-2

A

6.94

5.19

3.47

4.00

3.50

3.00

1.75

.22 x .59

9

120

23-22-112-2

A

8.12

5.19

3.47

4.00

3.50

3.00

2.44

.22 x .59

13

250

23-23-125-8

A

10.50

7.56

4.75

5.63

4.75

4.12

3.03

.39 x .69

28

500

23-23-150-8

A

13.00

6.50

8.12

9.00

8.12

5.62

3.06

.38 x .81

37

1000

23-23-210-8

A

17.25

6.81

8.12

9.00

8.12

5.62

5.25

.38 x .81

63

2000

23-23-220-8

B

17.58

9.44

10.56

12.75

11.75

3.88

5.19

.44 x .69

109

3000

23-23-230-8

B

18.96

9.44

10.56

12.75

11.75

5.25

5.19

.44 x .69

142

5000

23-23-250-8

B

28.53

9.44

10.56

12.75

11.75

8.25

8.88

.44 x .69

222

7500

23-28-275-6

C

26.91

9.27

23.55

25.81

24.81

6.62

8.88

.44 x .69

365

Three-Phase Power Wiring
If operation from a three-phase source is required, three hardwired regulators 

may be wired in delta as shown in Figure 4.

Other Considerations
It is desirable to have a switch in the input circuitry for turning off power to 

the unit when it is not in use. While all CVS transformers are designed for 

continuous duty, they draw appreciable current regardless of output loading. 

The outputs of all Sola/Hevi-Duty standard CVS transformers are isolated 

from the input lines. Voltage generated by internal leakage currents will occur 

with respect to ground. This can have undesirable effects in many pieces of 

electronic equipment. Therefore, if Figure 4 circuit “B” is used, it is suggested 

that the installer remove X2 grounding on –8 units, then connect all X2 from 

each phase to one location and ground at that location only.  This is not 

required for circuit “A”. This will not affect regulation or the ability to reject 

power line noise or transients.

Any three stock units having a tap for 190-260 input connections may be 

connected in delta to a 240-volt, three-phase power supply. Those units 

equipped with primary tap for 175-235 volts may also be connected in delta 

to a 208-volt supply. (Terminals to be used are identified on the connection 

diagram located on the inside face of the outlet box cover.)

All stock production, harmonic-free units now have uniform terminal polarity. 

This eliminates the need for “phasing out” either input or output connections.

Output must serve three, independent, single-phase loads of the same total 

volt-ampere rating. Connections should be made in one of two ways shown  

in Figure 4.

Use With Switchmode Power Supplies
If a CVS transformer is used as a source for a switchmode power supply, a 

slight amount of ringing may be noticed on the sinewave output of the CVS at 

half cycle intervals for a short duration. This ringing occurs at the point when 

the switchmode power supply current demand drops to zero.  The ringing 

should not be a cause for concern since it is of relatively low magnitude and 

frequency. The CVS has been tested with a variety of switchmode power 

supplies and it has been determined that the ringing never affects the D 

outputs, nor has it been found to degrade the components of any switchmode 

power supply.

Volts

Input

Jumper

Volts

Output

95-130

H1-H2

(H1 + H3 + H6 + H8)  (H2 + H5 + 

H7 + H10)

120

X1 – X2 or 

X2 – X3

175-235

H1-H4

(H2 + H3)  (H7 + H8)  (H1 + H6) 

(H4 + H9)

240

X1 – X3

190-260

H1-H5

(H2 + H3)  (H7 + H8)  (H1 + H6) 

(H5 + H10)

380-520

H1-H10

(H2 + H3)  (H5 + H6)  (H7 + H8)

Volts

Input

Jumper

Volts

Output

95-130

H1-H2

(H1 + H3 + H5 + H7)   

(H2 + H4 + H6 + H8)

120

X1 – X2

190-260

H1-H4

(H2 + H3)  (H6 + H7)   

(H1 + H5)  (H4 + H8)

380-520

H1-H8

(H2 + H3)  (H4 + H5)  

 (H6 + H7)

Primary Voltage

Interconnect

Connect 

Lines To

30 & 60 VA

120 VA

7500 VA

120

N/A

N/A

Note: H3 & H4

are not used

H1 & H2

N/A

120

240

H1 to H3

H2 to H4

H1 & H4

N/A

240

480

H2 to H3

H1 & H4

Secondary Voltage

Interconnect

Connect 

Lines To

30 & 60 VA

120 VA

7500 VA

120

120

N/A

X1 & X2

N/A

N/A

120

X1 & X2 or

H3 & X2

N/A

N/A

240

X1 & X3

CVS

Input

Output

VA Rating

Rated

Volts

Req. Circuit 

Protection 

(In Amps,)

Min. Gauge 

90°C Wire 

Rated

Volts

Min. Gauge

90°C Wire

30

95-130

1

14

120

14

60

2

120

95-130

3

14

120

14

190-260

250

95-130

6

14

120

14

190-260

3

380-520

1

500

95-130

10

14

120

208

240

14

175-235

6

190-260

6

380-520

3

1000

95-130

15

14

120

208

240

14

175-235

10

190-260

10

380-520

6

2000

95-130

30

10

120

208

240

10

14

14

175-235

20

12

190-260

15

14

380-520

10

14

3000

95-130

45

8

120

208

240

8

12

12

175-235

25

10

190-260

25

10

380-520

15

14

5000

95-130

80

4

120

208

240

8*

10

10

175-235

40

8

190-260

40

8

380-520

20

12

7500

190-260

60

6

120

208

240

4

380-520

30

10

8

3

2

1

6

5

4

7

9

8

0.650162s